Positive resist composition

ABSTRACT

A positive resist composition comprising: (A) a compound capable of generating an acid on exposure to active light rays or a radiation; (B) a resin which is insoluble or sparingly soluble in an alkali and becomes alkali-soluble by an action of an acid; and (D) an acyclic compound having at least three groups selected from a hydroxyl group and a substituted hydroxyl group.

FIELD OF THE INVENTION

This invention relates to a positive resist composition used infabrication of semiconductor devices, e.g., ICs, fabrication of circuitwiring boards for liquid crystals, thermal heads, etc., and otherphotofabrication techniques. More particularly, it relates to a positiveresist composition which is adapted to be exposed to far ultravioletrays of 250 nm or shorter wavelengths, electron beams, and the like.

BACKGROUND OF THE INVENTION

A chemically amplified positive-working resist composition is apatterning material which generates an acid on exposure to an radiation,such as far ultraviolet light, undergoes acid-catalyzed reaction tocreate a change in solubility in a developing solution between theexposed area and the non-exposed area thereby to form a pattern on asubstrate.

A photosensitive system designed to be exposed to light from a KrFexcimer laser mainly comprises a resin having a polyhydroxystyreneskeleton which exhibits a small absorption primarily at 248 nm. It is abetter system than a conventional naphthoquinonediazide/novolak resinsystem, enjoying high sensitivity, high resolution, and satisfactorypatterning performance.

When a light source of shorter wavelength, e.g., an ArF excimer laser(193 nm), is used as an exposure source, however, the above-describedchemically amplified system is insufficient because the compound havingan aromatic group essentially exhibits a large absorption at 193 nm.

Use of poly(meth)acrylate as a polymer having a small absorption at 193nm is reported in J. Vac, Sci. Technol., B9, 1991, 3357. This polymer isdisadvantageous in that it has lower resistance to dry etching generallyinvolved in semiconductor device fabrication than conventional phenolicresins having an aromatic group.

To cope with the ever increasing demands for finer patterning and higherthroughput, it has now come to be important to reduce exposure errors.Conventional resists have narrow exposure latitude and considerable lineedge roughness (LER), which have been a bar to increase the throughput.Further, with the recent trend toward finer dimensions of resistpatterns, collapse of a resist pattern has become problematic due to ahigh aspect ratio of height to width of resist lines. The patterncollapse problem is particularly conspicuous with resists designed forArF, electron beam (EB), vacuum ultraviolet (UVU) or extreme ultraviolet(EUV) radiations. The term “pattern collapse” as used herein is intendedto include any pattern collapse phenomena irrespective of the causes,for example, insufficient adhesion and insufficient film strength.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a positive resistcomposition capable of providing a resist pattern with reduced LER.

Another object of the present invention is to provide a positive resistcomposition capable of providing a resist pattern with minimizedcollapse, particularly a pattern that does not collapse even withvariations of focus and exposure in micro-patterning.

The above objects are accomplished by the following positive resistcomposition provided by the present invention.

-   (1) A positive resist composition comprising (A) a compound capable    of generating an acid on exposure to active light rays or a    radiation, (B) a resin which is insoluble or sparingly soluble in an    alkali and becomes alkali-soluble by the action of an acid, and (D)    an acyclic compound having at least three groups selected from a    hydroxyl group and a substituted hydroxyl group.

The present invention embraces the following compositions as preferredembodiments of the composition set forth in (1) above.

-   (2) A positive resist composition according to (1), wherein the    resin (B) has at least one phenolic hydroxyl group structure and    decomposes by the action of an acid to increase its solubility in an    alkali developing solution.-   (3) A positive resist composition according to (1), wherein the    resin (B) has a monocyclic or polycyclic alicyclic hydrocarbon    structure and decomposes by the action of an acid to increase its    solubility in an alkali developing solution.-   (4) A positive resist composition according to (1), wherein the    resin (B) has a structure containing a fluorine atom substituting at    least one of the main chain and the side chain of the polymer    skeleton and decomposes by the action of an acid to increase its    solubility in an alkali developing solution.-   (5) A positive resist composition according to any one of (1) to    (4), wherein the acyclic compound (D) is an acyclic saccharide    derivative.-   (6) A positive resist composition according to any one of (1) to    (5), which further comprises (C) a basic compound.-   (7) A positive resist composition according to any one of (1) to    (6), which further comprises (E) a surface active agent containing    at least one of fluorine and silicon.-   (8) A positive resist composition according to any one of (1) to    (7), which further comprises (F) a mixed solvent comprising a    solvent having a hydroxyl group and a solvent free from a hydroxyl    group.

DETAILED DESCRIPTION OF THE INVENTION

The positive resist composition of the invention contains a compoundcapable of generating an acid on exposure to active light rays or aradiation (hereinafter referred to as a photo-acid generator) ascomponent (A).

The photo-acid generator as component (A) is appropriately selected fromknown compounds and mixtures capable of generating an acid on exposureto active light rays or radiations, which have been used as photoinitiators for photo-cationic polymerization, photo initiators forphoto-radical polymerization, photobleaching agents for dyes,photo-discoloring agents, compounds used in microresists, and the like.Examples of useful photo-acid generators include onium salts, such asdiazonium salts, ammonium salts, phosphonium salts, iodonium salts,sulfonium salts, selenonium salts, and arsonium salts; organic halogencompounds; organometallic/organohalogen compounds; photo-acid generatorshaving an o-nitrobenzyl type protective group; compounds generatingsulfonic acid on photolysis which are represented by iminosulfonates;and disulfone compounds.

Polymers having the acid generating compound recited above or anacid-generating group derived therefrom in the main or side chainthereof are also useful as component (A). Examples of such polymericphoto-acid generators are given in U.S. Pat. No. 3849,137, German Patent3914407, JP-A-63-26653, JP-A-55-164824, JP-A-62-69263, JP-A-63-146038,JP-A-63-163452, JP-A-62-153853, and JP-A-63-146029. The photo-acidgenerating compounds disclosed in U.S. Pat. No. 3,779,778 and EP 126,712are also useful.

Of the above-recited photo-acid generators (A), the following fourgroups of compounds (A1) to (A4) are particularly effective.

(A1) Iodonium salts represented by formula (PAG1) and sulfonium saltsrepresented by formula (PAG2):

wherein Ar¹ and Ar² each represent a substituted or unsubstituted arylgroup; Ar¹ and Ar² may be connected via a single bond or a substituent;R²⁰³, R²⁰⁴, and R²⁰⁵ each represent a substituted or unsubstituted alkylgroup or a substituted or unsubstituted aryl group; two of R²⁰³, R²⁰⁴,and R²⁰⁵ may be connected via a single bond or a substituent; Zrepresents a counter anion.

Preferred substituents of the substituted aryl group as Ar¹ and Ar²include an alkyl group, a haloalkyl group, a cycloalkyl group, an arylgroup, an alkoxy group, a nitro group, a carboxyl group, analkoxycarbonyl group, a hydroxyl group, a mercapto group, and a halogenatom.

R²⁰³, R²⁰⁴, and R²⁰⁵ each preferably represent an aryl group having 6 to14 carbon atoms or a substituted derivative thereof or an alkyl grouphaving 1 to 8 carbon atoms or a substituted derivative thereof.Preferred substituents of the substituted aryl group include an alkoxygroup having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbonatoms, a nitro group, a carboxyl group, a hydroxyl group, and a halogenatom. Preferred substituents of the substituted alkyl group include analkoxy group having 1 to 8 carbon atoms, a carboxyl group, and analkoxycarbonyl group.

The counter anion Z⁻ includes, but is not limited to, BF₄ ⁻, AsF₆ ⁻, PF₆⁻, SbF₆ ⁻, SiF₆ ²⁻, ClO₄ ⁻, perfluoroalkanesulfonate anions (e.g.,CF₃SO₃ ⁻), pentafluorobenzenesulfonate anion, condensed polynucleicaromatic sulfonate anions (e.g., naphthalene-1-sulfonate anion), ananthraquinonesulfonate anion, and sulfonic group-containing dye anions.

Illustrative examples of the group (A1) compounds are shown below.

The onium salts represented by formulae (PAG1) and (PAG2) are knowncompounds, which can be synthesized by the processes taught in U.S. Pat.Nos. 2,807,648 and 4,247,473 and JP-A-53-101331.

(A2) Disulfonic acid derivatives represented by formula (PAG3) andiminosulfonate derivatives represented by formula (PAG4):

wherein Ar³ and Ar⁴ each represent a substituted or unsubstituted arylgroup; R²⁰⁶ represents a substituted or unsubstituted alkyl group or asubstituted or unsubstituted aryl group; and A represents a substitutedor unsubstituted alkylene group, a substituted or unsubstitutedalkenylene group or a substituted or unsubstituted arylene group.

Illustrative examples of the group (A2) compound are listed below.

(A3) Diazodisulfone derivatives represented by formula (PAG5):

wherein R represents a straight-chain, branched or cyclic alkyl group ora substituted or unsubstituted aryl group.

Illustrative examples of the group (A3) compounds are shown below.

(A4) Compounds represented by formula (PAG6):

wherein R₁, R₂, R₃, R₄, and R₅ each represent a hydrogen atom, an alkylgroup, an alkoxy group, a nitro group, a halogen atom, an alkoxycarbonylgroup or an aryl group; at least two of R₁ to R₅ may be taken togetherto form a cyclic structure; R₆ and R₇ each represent a hydrogen atom, analkyl group, a cyano group or an aryl group; Y₁ and Y2 each represent analkyl group, an aryl group, an aralkyl group or an aromatic groupcontaining a hetero atom; Y₁ and Y₂ may be taken together to form aring; Y₃ represents a single bond or a divalent linking group; X⁻represents a non-nucleophilic anion; provided that at least one of R₁ toR₅ and at least one of Y₁ and Y₂ are connected to form a ring, or atleast one of R₁ to R₅ and at least one of R₆ and R₇ are connected toform a ring.

The compound of formula (PAG6) includes a compound having two or morestructures represented by formula (PAG6) linked at any one of R₁ to R₇or either Y₁ or Y₂ via a linking group.

The alkyl group as represented by R₁ through R₇ is a substituted orunsubstituted alkyl group, preferably one having 1 to 5 carbon atoms asunsubstituted. The unsubstituted alkyl group includes methyl, ethyl,propyl, n-butyl, sec-butyl, and t-butyl.

The alkoxy group or the alkoxy moiety of the alkoxycarbonyl group asrepresented by R₁ through R₅ is a substituted or unsubstituted alkoxygroup, preferably one having 1 to 5 carbon atoms as unsubstituted.Examples of the unsubstituted alkoxy group are methoxy, ethoxy, propoxy,and butoxy.

The aryl group as R₁ to R₇, Y₁, and Y₂ is a substituted or unsubstitutedaryl group, preferably one having 6 to 14 carbon atoms as unsubstituted.Examples of the unsubstituted aryl group are phenyl, tolyl, andnaphthyl.

The halogen atom as R₁ to R₅ includes fluorine, chlorine, bromine, andiodine.

The alkyl group represented by Y₁ or Y₂ is a substituted orunsubstituted alkyl group, preferably one having 1 to 30 carbon atoms asunsubstituted. Examples of the unsubstituted alkyl group includestraight-chain or branched ones, e.g., methyl, ethyl, propyl, n-butyl,sec-butyl, and t-butyl; and cyclic ones, e.g., cyclopropyl, cyclopentyl,cyclohexyl, adamantyl, norbornyl, and bornyl.

The aralkyl group as Y₁ or Y₂ is a substituted or unsubstituted aralkylgroup, preferably one having 7 to 12 carbon atoms as unsubstituted.Examples of the unsubstituted aralkyl group are benzyl, phenethyl, andcumyl.

The term “aromatic group containing a hetero atom” denotes an aromaticgroup, such as an aryl group containing 6 to 14 carbon atoms, having ahetero atom, such as a nitrogen atom, an oxygen atom or a sulfur atom.The aromatic group containing a hetero atom as represented by Y₁ or Y₂is a substituted or unsubstituted aromatic group containing a heteroatom. Examples of the unsubstituted one include heterocyclic aromatichydrocarbon groups derived from, e.g., furan, thiophene, pyrrole,pyridine, and indole.

Y₁ and Y₂ may be connected together with S⁺ to form a ring. The groupformed of Y₁ and Y₂ includes an alkylene group having 4 to 10 carbonatoms, preferably butylene, pentylene, and hexylene, still preferablybutylene and pentylene. The ring formed of Y₁, Y₂, and S⁺ may contain anadditional hetero atom.

Substituents of the substituted alkyl, alkoxy, alkoxycarbonyl, aryl, andaralkyl groups include a nitro group, a halogen atom, a carboxyl group,a hydroxyl group, an amino group, a cyano group, and an alkoxy group(preferably one having 1 to 5 carbon atoms). Substituents of thesubstituted aryl or aralkyl group further include an alkyl group(preferably one having 1 to 5 carbon atoms). The substituent of thesubstituted alkyl group is preferably a halogen atom.

The divalent linking group as represented by Y₃ includes a substitutedor unsubstituted alkylene group, a substituted or unsubstitutedalkenylene group, —O—, —S—, —CO—, —CONR— (wherein R is a hydrogen atom,an alkyl group or an acyl group), and a combination of two or morethereof.

The term “non-nucleophilic anion” as to X⁻ refers to an anion havingvery low nucleophilic reactivity and therefore capable of inhibitingintramolecular nucleophilic reaction-induced decomposition with time.The resist exhibits improved stability with time in the presence of sucha non-nucleophilic anion. The non-nucleophilic anion as X⁻ includessulfonate anions and carboxylate anions.

The sulfonate anions include alkylsulfonate anions, arylsulfonateanions, and camphorsulfonate anions. The carboxylate anions includealkylcarboxylyate anions, arylcarboxylate anions, and aralkycarboxylateanions.

The alkyl moiety in the alkylsulfonate anions is preferably onecontaining 1 to 30 carbon atoms, such as methyl, ethyl, propyl,isopropyl, n-butyl, isobutyl, sec-butyl, pentyl, neopentyl, hexyl,heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl,pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl,cyclopropyl, cyclopentyl, cyclohexyl, adamantyl, norbornyl, or bornyl.The aryl moiety in the arylsulfonate anions is preferably one containing6 to 14 carbon atoms, such as phenyl, tolyl or naphthyl.

The alkyl or the aryl moiety in the alkylsulfonate anions and thearylsulfonate anions may have a substituent. Examples of the substituentare a halogen atom, an alkyl group, an alkoxy group, and an alkylthiogroup. The halogen atom includes chlorine, bromine, fluorine, andiodine. The alkyl group is preferably one having 1 to 15 carbon atom,such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl,pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl,tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl,nonadecyl or eicosyl. The alkoxy group is preferably one having 1 to 5carbon atoms, such as methoxy, ethoxy, propoxy or butoxy. The alkylthiogroup is preferably one having 1 to 15 carbon atoms, such as methylthio,ethylthio, propylthio, isopropylthio, n-butylthio, isobutylthio,sec-butylthio, pentylthio, neopentylthio, hexylthio, heptylthio,octylthio, nonylthio, decylthio, undecylthio, dodecylthio, tridecylthio,tetradecylthio, pentadecylthio, hexadecylthio, heptadecylthio,octadecylthio, nonadecylthio or eicosylthio. These alkyl, alkoxy oralkylthio groups may be substituted with a halogen atom, preferably afluorine atom.

The alkyl moiety in the alkylcarboxylate anions include those recitedabove as for the alkyl moiety in the alkylsulfonate anions. The arylmoiety in the arylcarboxylate anions include those recited above as forthe aryl moiety in the arylsulfonate anions. The aralkyl moiety in thearalkylcarboxylate anions is preferably one having 6 to 12 carbon atoms,such as benzyl, phenethyl, naphthylmethyl or naphthylethyl.

The alkyl moiety, aryl moiety, and aralkyl moiety in thealkylcarboxylate anions, arylcarboxylate anions, and aralkylcarboxylateanions may have a substituent. The substituent includes the samehalogen, alkyl, alkoxy and alkylthio substituents as recited as for thearylsulfonate anions.

Further included in the non-nucleophilic anions are a fluorophosphateanion, a fluoroborate anion, and a fluoroantimonate anion.

In formula (PAG6), at least one of R₁ to R₅ and at least one of Y₁ andY₂ are connected to form a ring, or at least one of R₁ to R₅ and atleast one of R₆ and R₇ are connected to form a ring. Because the ringstructure fixes the steric configuration, the compound of formula (PAG6)exhibits improved photolytic properties.

Two or more structures represented by formula (PAG6) may be linked atany one of R₁ to R₇ or either Y₁ or Y₂ via a linking group.

The compound of formula (PAG6) is preferably represented by formula(PAG6A) or (PAG6B):

wherein R₁, R₂, R₃, R₄, R₇, Y₁, Y₂, and X⁻ are as defined above; and Yrepresents a single bond or a divalent linking group.

In formulae (PAG6A) and (PAG6B), the divalent linking group as Ypreferably includes a substituted or unsubstituted alkylene group, asubstituted or unsubstituted alkenylene group, —O—, —S—, —CO—, —CONR—(wherein R is a hydrogen atom, an alkyl group or an acyl group), and acombination of two or more thereof.

In formula (PAG6A), Y preferably represents an alkylene group, anoxygen-containing alkylene group or a sulfur-containing alkylene group,such as methylene, ethylene, propylene, —CH₂—O— or —CH₂—S—, particularlya linking group forming a 6-membered ring, such as ethylene, —CH₂—O— or—CH₂—S—. When the Y-containing ring in formula (PAG6A) is a 6-memberedring, the angle between the carbonyl plane and the C—S⁺ sigma bond iscloser to a right angle so that the photolysis efficiency is improved byorbital interaction.

The compound represented by formula (PAG6A) can be synthesized byreacting a corresponding a-halo cyclic ketone and a sulfide compound orconverting a corresponding cyclic ketone to a silyl enol ether, which isthen reacted with a sulfoxide. The compound of formula (PAG6B) isobtained by reacting an aryl alkyl sulfide with an α- or β-halogenatedcompound.

Specific but non-limiting examples of the group (A4) compounds are shownbelow.

Preferred of these acid-generators of formulae (PAG6A) and (PAG6B) are(PAG6A-1) to (PAG6A-30) and (PAG6B-1) to (PAG6B-12).

The compounds of formula (PAG6) can be used either individually or as acombination of two or more thereof.

The photo-acid generator (A) is preferably used in an amount of 0.1 to20% by weight, particularly 0.5 to 20% by weight, especially 1 to 15% byweight, based on the total solids content of the positive resistcomposition.

Of the above-described photo-acid generators as component (A) thefollowing compounds are particularly preferred.

The positive resist composition of the invention contains, as component(B), a resin which is insoluble or sparingly soluble in an alkali andbecomes alkali-soluble by the action of an acid (hereinafter referred toas an acid-degradable resin). The acid-degradable resin (B) is notparticularly limited as long as the above solubility requirements arefulfilled. The functional group serving for alkali solubility ispreferably a phenolic hydroxyl group or a carboxyl group.

A preferred acid-degradable resin (B) is a resin which has at least onephenolic hydroxyl group structure and decomposes by the action of anacid to increase its solubility in an alkali developing solution. Such aresin includes a resin having at least a p-hydroxystyrene unit.Poly-p-hydroxystyrene part of which is protected with anacid-decomposable group, a p-hydroxystyrene/t-butyl acrylate copolymer,or a derivative thereof is still preferred. Useful acid-degradableresins (B) are shown below.

A resin which has a monocyclic or polycyclic alicyclic hydrocarbonstructure and increases its solubility in an alkali developing solutionby the action of an acid is also preferred as component (B) Inparticular, a resin having at least one repeating unit selected from thegroup consisting of a unit having an alicyclic hydrocarbongroup-containing partial structure represented by formula (pI), (pII),(pIII), (pIV), (pV) or (pVI) and a unit represented by formula (II-AB):

wherein R₁₁ represents a methyl group, an ethyl group, an n-propylgroup, an isopropyl group, an n-butyl group, an isobutyl group or asec-butyl group; Z represents an atomic group necessary to form analicyclic hydrocarbon group together with the adjacent carbon atom; R₁₂,R₁₃, R₁₄, R₁₅, and R₁₆ each represent a straight-chain or branched alkylgroup having 1 to 4 carbon atoms or an alicyclic hydrocarbon group,provided that at least one of R₁₂, R₁₃, and R₁₄ and at least one of R₁₅and R₁₆ represent an alicyclic hydrocarbon group; R₁₇, R₁₈, R₁₉, R₂₀,and R₂₁ each represent a hydrogen atom, a straight-chain or branchedalkyl group having 1 to 4 carbon atoms or an alicyclic hydrocarbongroup, provided that at least one of R₁₇, R₁₈, R₁₉, R₂₀, and R₂₁represents an alicyclic hydrocarbon group and that at least one of R₁₉and R₂₁ represents a straight-chain or branched alkyl group having 1 to4 carbon atoms or an alicyclic hydrocarbon group; and R₂₂, R₂₃, R₂₄, andR₂₅ each represent a straight-chain or branched alkyl group having 1 to4 carbon atoms or an alicyclic hydrocarbon group, provided that at leastone of R₂₂, R₂₃, R₂₄, and R₂₅ represents an alicyclic hydrocarbon group;and R₂₃ and R₂₄ may be connected together to form a ring.

wherein R_(11′) and R_(12′) each represent a hydrogen atom, a cyanogroup, a halogen atom or a substituted or unsubstituted alkyl group; andZ′ represents an atomic group necessary to form a substituted orunsubstituted alicyclic structure containing the two bonded carbon atoms(C—C).

The unit represented by formula (II-AB) is preferably represented byformula (II-A) or (II-B):

wherein R_(13′), R_(14′), R₁₅′, and R_(16′) each represent a hydrogenatom, a halogen atom, a cyano group, —COOH, —COOR₅, a group decomposableby the action of an acid, —C(═O)—X-A′-R_(17′), a substituted orunsubstituted alkyl group or a substituted or unsubstituted cyclichydrocarbon group; wherein

-   -   R₅ represents a substituted or unsubstituted alkyl group, a        substituted or unsubstituted cyclic hydrocarbon group or a group        —Y represented by formulae shown below;    -   X represents an oxygen atom, a sulfur atom, —NH—, —NHSO₂— or        —NHSO₂NH—; A′ represents a single bond or a divalent linking        group; R_(17′) represents —COOH, —COOR₅, —CN, a hydroxyl group,        a substituted or unsubstituted alkoxy group, —CO—NH—R₆,        —CO—NH—SO₂—R₆ or a group —Y; and R₆ represents a substituted or        unsubstituted alkyl group or a substituted or unsubstituted        cyclic hydrocarbon group;        two or more of R_(13′), R_(14′), R_(15′), and R_(16′)may be        taken together to form a ring; and n represents 0 or 1.

The group —Y is represented by formula:

wherein R_(21′), R_(22′), R_(23′), R_(24′), R_(25′), R_(26′), R_(27′),R_(28′), R_(29′), and R_(30′) each represent a hydrogen atom or asubstituted or unsubstituted alkyl group; and a and b each represent 1or 2.

In formulae (pI) to (pVI), the alkyl group as R₁₂ to R₂₅ is asubstituted or unsubstituted straight-chain or branched one having 1 to4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl or t-butyl. The substituent of the substituted alkylgroup includes an alkoxy group having 1 to 4 carbon atoms, a halogenatom (e.g., fluorine, chlorine, bromine or iodine), an acyl group, anacyloxy group, a cyano group, a hydroxyl group, a carboxyl group, analkoxycarbonyl group, and a nitro group.

The alicyclic hydrocarbon group as represented by R₁₂ to R₂₅ or asformed by Z and the adjacent carbon atom may be monocyclic or polycyclicand includes groups having a monocyclic, bicyclic, tricyclic,tetracyclic or like cyclic structure containing 5 or more carbon atoms.The carbon atom number of the alicyclic hydrocarbon group (asunsubstituted) is preferably 6 to 30, still preferably 7 to 25. Thealicyclic hydrocarbon group may have a substituent. Examples of thealicyclic moiety of the alicyclic hydrocarbon group are shown below.

Preferred of these alicyclic moieties are adamantyl, noradamantyl,decalyl, tricyclodecanyl, tetracyclododecanyl, norbornyl, cedryl,cyclohexyl, cycloheptyl, cyclooctyl, cyclodecanyl, and cyclododecanyl.Still preferred are adamantyl, decalyl, norbornyl, cedryl, cyclohexyl,cycloheptyl, cyclooctyl, cyclodecanyl, and cyclododecanyl.

The substituent the alicyclic hydrocarbon group can have includes analkyl group, a substituted alkyl group, a halogen atom, a hydroxylgroup, an alkoxy group, a carboxyl group, and an alkoxycarbonyl group.The alkyl group is preferably a lower one, e.g., methyl, ethyl, propyl,isopropyl or butyl, still preferably methyl, ethyl, propyl or isopropyl.The substituent of the substituted alkyl group includes a hydroxylgroup, a halogen atom, and an alkoxy group. The alkoxy group ispreferably one having 1 to 4 carbon atoms, e.g., methoxy, ethoxy,propoxy or butoxy.

The structures represented by formulae (pI) through (pVI) can serve forprotection of an alkali-soluble group. The alkali-soluble group includesvarious groups known in the art, such as a carboxyl group, a sulfogroup, a phenol group, and a thiol group, with a carboxyl group and asulfo group being preferred.

The alkali-soluble groups protected with the structures of formula (pI)through (pVI) preferably include those shown below.

wherein R₁₁ to R₂₅ and Z are as defined above.

The repeating unit having an alkali-soluble group protected with thestructures of formulae (pI) to (pVI) which constitutes theabove-described resin (B) is preferably represented by formula (pA):

wherein a plurality of R groups, which may be the same or different,each represent a hydrogen atom, a halogen atom or a substituted orunsubstituted straight-chain or branched alkyl group having 1 to 4carbon atoms; A represents a single bond or one of, or a combination oftwo or more of, an alkylene group, a substituted alkylene group, anether group, a thioether group, a carbonyl group, an ester group, anamide group, a sulfonamide group, a urethane group, and a urea group;and Ra represents any one of the structures represented by formulae (pI)to (pVI).

Examples of the monomers providing the repeating unit of formula (pA)are shown below.

In formula (II-AB), R_(11′) and R_(12′) each represent a hydrogen atom,a cyano group, a halogen atom or a substituted or unsubstituted alkylgroup; and Z′ represents an atomic group necessary to form a substitutedor unsubstituted alicyclic structure containing the two bonded carbonatoms (C—C).

The halogen atom as R_(11′) or R_(12′) includes chlorine, bromine,fluorine, and iodine.

The alkyl group as R_(11′), R_(12′), and R_(21′) to R_(30′) (in formulae(II-A) and (II-B)) is preferably a straight-chain or branched one having1 to 10 carbon atoms, still preferably a straight-chain or branched onehaving 1 to 6 carbon atoms, particularly preferably methyl, ethyl,propyl, isopropyl, n-butyl, isobutyl, sec-butyl or t-butyl.

The substituent of the substituted alkyl group as R_(11′), R_(12′), andR_(21′) to R_(30′) includes a hydroxyl group, a halogen atom, a carboxylgroup, an alkoxy group, an acyl group, a cyano group, and an acyloxygroup. The halogen atom includes chlorine, bromine, fluorine, andiodine. The alkoxy group includes one having 1 to 4 carbon atoms, e.g.,methoxy, ethoxy, propoxy or butoxy. The acyl group includes formyl andacetyl. The acyloxy group includes acetoxy.

The atomic group Z′ necessary to form the alicyclic structure is toprovide a repeating unit with a substituted or unsubstituted alicyclichydrocarbon. In particular, Z′ is preferably an atomic group forming abridged alicyclic structure providing a bridged alicyclic hydrocarbonrepeating unit.

Skeletons of the alicyclic hydrocarbons formed by Z′ are shown below.

Of the bridged alicyclic hydrocarbon skeletons shown above preferred are(5) to (7), (9), (10), (13) to (15), (23), (28), 36), (37), (42), and(47).

The above-described alicyclic hydrocarbon skeletons may have asubstituent. The substituent includes the atoms (except hydrogen) andgroups recited as R_(13′), R_(14′), R_(15′), and R_(16′) of formulae(II-A) and (II-B).

Of the repeating units having a bridged alicyclic hydrocarbon skeleton,those represented by formulae (II-A) and (II-B) are still preferred.

In formulae (II-A) and (II-B), R_(13′), R_(14′), R_(15′), and R_(16′)each represent a hydrogen atom, a halogen atom, a cyano group, —COOH,—COOR₅, a group decomposable by the action of an acid,—C(═O)—X-A′-R_(17′), a substituted or unsubstituted alkyl group or asubstituted or unsubstituted cyclic hydrocarbon group. R₅ represents asubstituted or unsubstituted alkyl group, a substituted or unsubstitutedcyclic hydrocarbon group or a group —Y represented by formulae shownabove. X represents an oxygen atom, a sulfur atom, —NH—. —NHSO₂— or—NHSO₂NH—. A′ represents a single bond or a divalent linking group.R_(17′) represents —COOH, —COOR₅, —CN, a hydroxyl group, a substitutedor unsubstituted alkoxy group, —CO—NH—R₆, —CO—NH—SO₂—R₆ or a group —Y.R₆ represents a substituted or unsubstituted alkyl group or asubstituted or unsubstituted cyclic hydrocarbon group. Two or more ofR_(13′), R_(14′), R_(15′), and R_(16′) may be taken together to form aring. n represents 0 or 1.

In the group —Y, R_(21′) to R_(30′) each represent a hydrogen atom or asubstituted or unsubstituted alkyl group; and a and b each represent 1or 2.

The acid-degradable group may be present in —C(═O)—X-A′-R_(17′) or as asubstituent of Z′ of formula (II-AB).

The acid-degradable group is represented by formula: —C(═O)—X₁–R₀,wherein R₀ represents a tertiary alkyl group (e.g., t-butyl or t-amyl),an isobornyl group, a 1-alkoxyethyl group (e.g., 1-ethoxyethyl,1-butoxyethyl, 1-isobutoxyethyl or 1-cyclohexyloxyethyl), analkoxymethyl group (e.g., 1-methoxymethyl or 1-ethoxymethyl), a3-oxoalkyl group, a tetrahydropyranyl group, a tetrahydrofuranyl group,a trialkylsilyl ester group, a 3-oxocyclohexyl ester group, a2-methyl-2-adamantyl group, a mevalonic lactone residue, etc.; and X₁has the same meaning as X.

The halogen atom as R_(13′) to R_(16′) includes chlorine, bromine,fluorine, and iodine.

The alkyl group as R₅, R₆, and R_(13′) to R_(16′) is preferably astraight-chain or branched one having 1 to 10 carbon atoms, stillpreferably a straight-chain or branched one having 1 to 6 carbon atoms,particularly preferably methyl, ethyl, propyl, isopropyl, n-butyl,isobutyl, sec-butyl or t-butyl.

The cyclic hydrocarbon group as R₅, R₆, and R_(13′) to R_(16′) includesa cyclic alkyl group and a bridged hydrocarbon group, such ascyclopropyl, cyclopentyl, cyclohexyl, adamantyl, 2-methyl-2-adamantyl,norbornyl, bornyl, isobornyl, tricyclodecanyl, dicyclopentenyl,epoxynorbornyl, menthyl, isomenthyl, neomenthyl, andtetracyclododecanyl.

The ring formed of two or more of R_(13′) to R₁₆, includes a ring having5 to 12 carbon atoms, such as cyclopentene, cyclohexene, cycloheptane,and cyclooctane.

The alkoxy group as R_(17′) includes one containing 1 to 4 carbon atoms,such as methoxy, ethoxy, propoxy or butoxy.

The substituents of the alkyl group, cyclic hydrocarbon group, andalkoxy group include a hydroxyl group, a halogen atom (e.g., chlorine,bromine, fluorine or iodine), a carboxyl group, an alkoxy group (forexample, one having 1 to 4 carbon atoms, e.g., methoxy, ethoxy, propoxyor butoxy), an acyl group (e.g., formyl or acetyl), a cyano group, anacyloxy group (e.g., acetoxy), an alkyl group, and a cyclic hydrocarbongroup. The alkyl group and the cyclic hydrocarbon group include thoserecited above.

The divalent linking group as represented by A′ includes an alkylenegroup, a substituted alkylene group, an ether group, a thioether group,a carbonyl group, an ester group, an amide group, a sulfonamide group, aurethane group, a urea group, and a combination of two or more thereof.The substituted or unsubstituted alkylene group as A′ includes thoserepresented by —[C(R_(a)) (R_(b))]_(r)—, wherein R_(a) and R_(b), whichmay be the same or different, each represent a hydrogen atom, asubstituted or unsubstituted alkyl group, a halogen atom, a hydroxylgroup or an alkoxy group, and r presents an integer of 1 to 10. Thealkyl group is preferably a lower one, such as methyl, ethyl, propyl,isopropyl or butyl, still preferably methyl, ethyl, propyl or isopropyl.The substituent the alkyl group can have includes a hydroxyl group, ahalogen atom (e.g., chlorine, bromine, fluorine or iodine), and analkoxy group (such as one having 1 to 4 carbon atoms, e.g., methoxy,ethoxy, propoxy or butoxy).

The group decomposable by the action of an acid can be incorporated intoat least one of the repeating unit having an alicyclic hydrocarbongroup-containing partial structure represented by formulae (pI) to(pVI), the repeating unit represented by formula (II-AB), and arepeating unit derived from a comonomer described infra.

The atom or atomic group represented by R_(13′) to R_(16′) in formula(II-A) or (II-B) can be a substituent of the atomic group Z′ which isnecessary to form a (bridged) alicyclic structure in formula (II-AB).

Specific but non-limiting examples of the repeating units represented byformula (II-A) or (II-B) are shown below.

The acid-degradable resin (B) according to the present invention canfurther comprise a repeating unit having a lactone moiety andrepresented by formula (IV):

wherein R_(1a) represents a hydrogen atom or a methyl group; W₁represents a single bond or one of, or a combination of two or more of,an alkylene group, an ether group, a thioether group, a carbonyl group,and an ester group; and Lc represents a lactone structure of formula:

-   -   wherein R_(a1), R_(b1), R_(c1), R_(d1), and R_(e1) each        represent a hydrogen atom or an alkyl group having 1 to 4 carbon        atoms;    -   and m and n each represent an integer of 0 to 3, provided that        m+n is 2 to 6.

The C₁₋₄ alkyl group as R_(a1) to R_(e1) includes methyl, ethyl, propyl,isopropyl, n-butyl, isobutyl, sec-butyl, and t-butyl.

The alkylene group as W₁ includes a group represented by formula:—[C(R_(f)) (R_(g))]_(r1)—, wherein R_(f) and R_(g), which may be thesame or different, each represent a hydrogen atom, an alkyl group, asubstituted alkyl group, a halogen atom, a hydroxyl group or an alkoxygroup; and r1 represents an integer of 1 to 10. The alkyl group in thealkylene group is preferably a lower one, e.g., methyl, ethyl, propyl,isopropyl or butyl, still preferably methyl, ethyl, propyl or isopropyl.The substituent of the substituted alkyl group in the alkylene groupincludes a hydroxyl group, a halogen atom, and an alkoxy group. Thealkoxy group in the alkylene group includes one having 1 to 4 carbonatoms, e.g., methoxy, ethoxy, propoxy or butoxy. The halogen atomincludes chlorine, bromine, fluorine, and iodine.

Substituents of the substituted alkyl group include a carboxyl group, anacyloxy group, a cyano group, an alkyl group, a substituted alkyl group,a halogen atom, a hydroxyl group, an alkoxy group, a substituted alkoxygroup, an acetylamide group, an alkoxycarbonyl group, and an acyl group.The alkyl group as a substituent includes a lower one, such as methyl,ethyl, propyl, isopropyl, butyl, cyclopropyl, cyclobutyl or acyclopentyl. The substituent of the substituted alkyl group includes ahydroxyl group, a halogen atom, and an alkoxy group. The substituent ofthe substituted alkoxy group includes an alkoxy group. The alkoxy groupincludes a lower one having 1 to 4 carbon atoms, such as methoxy,ethoxy, propoxy or butoxy. The acyloxy group includes an acetoxy group.The halogen atom includes chlorine, bromine, fluorine, and iodine.

Specific but non-limiting examples of the repeating units of formula(IV) are shown below.

From the standpoint of a wider exposure latitude, repeating units(IV-17) to (IV-36) are preferred. From the standpoint of improved LER,those having an acrylate structure are preferred.

The resin (B) of the present invention can have a repeating unit havinga group represented by formula (V-1), (V-2), (V-3) or (V-4):

wherein R_(1b), R_(2b), R_(3b), R_(4b), and R_(5b) each represent ahydrogen atom, a substituted or unsubstituted alkyl group, a substitutedor unsubstituted cycloalkyl group or a substituted or unsubstitutedalkenyl group, and two out of R_(1b), R_(2b), R_(3b), R_(4b), and R_(5b)may be taken together to form a ring.

The alkyl group as R_(1b) to R_(5b) may be straight or branched andsubstituted or unsubstituted. The alkyl group preferably contains 1 to12, particularly 1 to 10, carbon atoms (as unsubstituted). Especiallypreferred alkyl groups are methyl, ethyl, propyl, isopropyl, n-butyl,isobutyl, sec-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, anddecyl.

The cycloalkyl group as R_(1b) to R_(5b) is preferably one containing 3to 8 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl,cycloheptyl or cyclooctyl.

The alkenyl group as R_(1b) to R_(5b) is preferably one containing 2 to6 carbon atoms, such as vinyl, propenyl, butenyl or hexenyl.

The ring formed of two of R_(1b) through R_(5b) includes a 3- to8-membered one, such as cyclopropane, cyclobutane, cyclopentane,cyclohexane or cyclooctane.

In formulae (V-1) through (V-4), R_(1b) to R_(5b) may be bonded to anycarbon atoms making up the cyclic skeleton.

Substituents that the alkyl, cycloalkyl or alkenyl group may haveinclude an alkoxy group containing 1 to 4 carbon atoms, a halogen atom(e.g., fluorine, chlorine, bromine or iodine), an acyl group having 2 to5 carbon atoms, an acyloxy group having 2 to 5 carbon atoms, a cyanogroup, a hydroxyl group, a carboxyl group, an alkoxycarbonyl grouphaving 2 to 5 carbon atoms, and a nitro group.

The repeating units having the group represented by formulae (V-1) to(V-4) include the units represented by formula (II-A) or (II-B) whereinat least one of R_(13′), R_(14′), R_(15′), and R_(16′) has the group offormula (V-1), (V-2), (V-3) or (V-4) (for example, at least one ofR_(13′) to R_(16′) is —COOR₅, wherein R₅ is the group of formula (V-1),(V-2), (V-3) or (V-4)) and a repeating unit represented by formula (AI):

wherein R_(b0) represents a hydrogen atom, a halogen atom or asubstituted or unsubstituted alkyl group having 1 to 4 carbon atoms; A′represents a single bond or a divalent linking group selected from anether group, an ester group, a carbonyl group, an alkylene group, and acombination thereof; and B₂ represents a group represented by any offormulae (V-1) to (V-4).

Preferred substituents of the substituted alkyl group as R_(b0) includethose recited supra as preferred substituents of the substituted alkylgroup represented by R_(1b) in formulae (V-1) through (V-4). The halogenatom as R_(b0) includes a fluorine atom, a chlorine atom, a bromineatom, and an iodine atom. R_(b0) is preferably a hydrogen atom. Thecombination of linking groups as A′ includes the following groups.

wherein R_(ab) and R_(bb), which may be the same or different, eachrepresent a hydrogen atom, an alkyl group, a substituted alkyl group, ahalogen atom, a hydroxyl group or an alkoxy group; m represents aninteger of 1 to 3; and r1 represents an integer of 1 to 10.

The alkyl group as R_(ab) or R_(bb) is preferably a lower one, such asmethyl, ethyl, propyl, isopropyl or butyl, still preferably methyl,ethyl, propyl or isopropyl. The substituent of the substituted alkylgroup includes a hydroxyl group, a halogen atom, and an alkoxy grouphaving 1 to 4 carbon atoms. The alkoxy group as R_(ab) or R_(bb)includes one having 1 to 4 carbon atoms, such as methoxy, ethoxy,propoxy or butoxy. The halogen atom includes chlorine, bromine,fluorine, and iodine. m is preferably 1 or 2. r1 is preferably 1 to 4.

Specific but non-limiting examples of the repeating unit represented byformula (AI) are shown below.

The acid-degradable resin (B) can further comprise a repeating unitrepresented by formula (VI):

wherein R_(6a) represents a hydrogen atom, an alkyl group having 1 to 4carbon atoms, a cyano group or a halogen atom; A₆ represents a singlebond or one of, or a combination of two or more of, an alkylene group, acycloalkylene group, an ether group, a thioether group, a carbonylgroup, and an ester group; and Z₆ represents —O—C(═O)— or —C(═O)—O—.

In formula (VI), the alkylene group as A₆ includes a group representedby formula: —[C(R_(nf)) (R_(ng))]_(r)—, wherein R_(nf) and R_(ng), whichmay be the same or different, each represent a hydrogen atom, an alkylgroup, a substituted alkyl group, a halogen atom, a hydroxyl group or analkoxy group; and r represents an integer of 1 to 10. The alkyl group inthe alkylene group is preferably a lower one, e.g., methyl, ethyl,propyl, isopropyl or butyl, still preferably methyl, ethyl, propyl orisopropyl. The substituent of the substituted alkyl group in thealkylene group includes a hydroxyl group, a halogen atom, and an alkoxygroup. The alkoxy group includes one having 1 to 4 carbon atoms, e.g.,methoxy, ethoxy, propoxy or butoxy. The halogen atom includes chlorine,bromine, fluorine, and iodine.

The cycloalkylene group as A₆ includes one having 3 to 10 carbon atoms,such as cyclopentylene, cyclohexylene or cyclooctylene.

The bridged alicyclic ring containing Z₆ may have a substituent, such asa halogen atom, an alkoxy group (preferably one having 1 to 4 carbonatoms), an alkoxycarbonyl group (preferably one having 1 to 5 carbonatoms), an acyl group (e.g., formyl or benzoyl), an acyloxy group (e.g.,propylcarbonyloxy or benzoyloxy), an alkyl group (preferably one having1 to 4 carbon atoms), a carboxyl group, a hydroxyl group, and analkylsulfonylsulfamoyl group (e.g., —CONHSO₂CH₃). The alkyl group as asubstituent may be substituted with a hydroxyl group, a halogen atom, analkoxy group (preferably one having 1 to 4 carbon atoms), etc.

In formula (VI), the oxygen atom of the ester group linking A₆ and thebridged alicyclic ring may be bonded to any carbon atom of the bridgedalicyclic ring.

Specific but non-limiting examples of the repeating unit represented byformula (VI) are shown below.

The acid-degradable resin (B) may comprise a repeating unit having agroup represented by formula (VII):

wherein R_(2c), R_(3c), and R_(4c) each represent a hydrogen atom or ahydroxyl group, provided that at least one of them is a hydroxyl group.

It is preferred that one or two of R_(2c), R_(3c), and R_(4c) representa hydroxyl group. It is still preferred that one of R_(2c), R_(3c), andR_(4c) be a hydroxyl group.

The repeating units having the group represented by formulae (VII)include the units represented by formula (II-A) or (II-B) wherein atleast one of R_(13′), R_(14′), R_(15′), and R_(16′) has the group offormula (VII) (for example, at least one of R_(13′) to R_(16′) is—COOR₅, wherein R₅ is the group of formula (VII)) and a repeating unitrepresented by formula (AII):

wherein R_(1c) represents a hydrogen atom or a methyl group; and R_(2c),R_(3c), and R_(4c) are as defined above.

Specific but non-limiting examples of the repeating units represented byformula (AII) are shown below.

The acid-degradable resin (B) may further comprise a repeating unitrepresented by formula (VIII):

wherein Z₂ represents —O— or —N(R₄₁)—; R₄₁ represents a hydrogen atom, ahydroxyl group, an alkyl group, a haloalkyl group or —OSO₂—R₄₂; and R₄₂represents an alkyl group, a haloalkyl group, a cycloalkyl group or acamphor residual group.

The alkyl group as R₄₁ or R₄₂ is preferably a straight-chain or branchedone having 1 to 10 carbon atoms, still preferably a straight-chain orbranched one having 1 to 6 carbon atoms, particularly preferably methyl,ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl or t-butyl. Thehaloalkyl group as R₄₁ or R₄₂ includes trifluoromethyl, nanofluorobutyl,pentadecafluorooctyl, and trichloromethyl. The cycloalkyl group as R₄₂includes cyclopentyl, cyclohexyl, and cyclooctyl.

The alkyl group and the haloalkyl group as R₄₁ or R₄₂ and the cycloalkylgroup and the camphor residue as R₄₂ may have a substituent. Thesubstituent includes a hydroxyl group, a carboxyl group, a cyano group,a halogen atom (e.g., chlorine, bromine, fluorine or iodine), an alkoxygroup (preferably one having 1 to 4 carbon atoms, e.g., methoxy, ethoxy,propoxy or butoxy), an acyl group (preferably one having 2 to 5 carbonatoms, e.g., formyl or acetyl), an acyloxy group (preferably one having2 to 5 carbon atoms, e.g., acetoxy), and an aryl group (preferably onehaving 6 to 14 carbon atoms, e.g., phenyl).

The repeating unit represented by formula (VIII) includes, but is notlimited to, the following units (I′-1) to (I′-7).

The acid-degradable resin (B) may further comprise various repeatingunits other than those described above for the purpose of improving dryetching resistance, suitability to standard developing solutions,adhesion to a substrate, resist profile, and basic characteristicsrequired of a resist, such as resolution, heat resistance, andsensitivity. Useful comonomers providing the other repeating unitsinclude, but are not limited to, compounds having one additionpolymerizable unsaturated bond, such as acrylic esters, methacrylicesters, acrylamides, methacrylamides, allyl compounds, vinyl ethers, andvinyl esters. Incorporation of these repeating units enables fineadjustment of various performance properties required of theacid-degradable resin, particularly solubility in a solvent for coating,film-forming properties (controllable by glass transition pointadjustment), alkali developability, resistance to resist film thicknessloss (controllable by hydrophilicity or hydrophobicity adjustment and byselection of an alkali soluble group), adhesion (of an unexposedportion) to a substrate, and dry etching resistance.

The acrylic esters include alkyl esters, preferably those having 1 to 10carbon atoms in the alkyl moiety. Examples are methyl acrylate, ethylacrylate, propyl acrylate, amyl acrylate, cyclohexyl acrylate,ethylhexyl acrylate, octyl acrylate, t-octyl acrylate, chloroethylacrylate, 2-hydroxyethyl acrylate, 2,2-dimethylhydroxypropyl acrylate,5-hydroxypentyl acrylate, trimethylolpropane monoacrylate,pentaerythritol monoacrylate, benzyl acrylate, methoxybenzyl acrylate,furfuryl acrylate, and tetrahydrofurfuryl acrylate.

The methacrylic esters include alkyl esters, preferably those having 1to 10 carbon atoms in the alkyl moiety. Examples are methylmethacrylate, ethyl methacrylate, propyl methacrylate, isopropylmethacrylate, amyl methacrylate, hexyl methacrylate, cyclohexylmethacrylate, benzyl methacrylate, chlorobenzyl methacrylate, octylmethacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate,5-hydroxypentyl methacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate,trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate,furfuryl methacrylate, and tetrahydrofurfuryl methacrylate.

The acrylamides include acrylamide, N-alkylacrylamides having an alkylmoiety containing 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl,butyl, t-butyl, heptyl, octyl, cyclohexyl or hydroxyethyl),N,N-dialkylacrylamides having an alkyl group containing 1 to 10 carbonatoms (e.g., methyl, ethyl, butyl, isobutyl, ethylhexyl or cyclohexyl),N-hydroxyethyl-N-methylacrylamide, andN-2-acetamidoethyl-N-acetylacrylamide.

The methacrylamides include methacrylamide, N-alkylmethacrylamideshaving an alkyl moiety containing 1 to 10 carbon atoms (e.g., methyl,ethyl, t-butyl, ethylhexyl, hydroxyethyl or cyclohexyl),N,N-dialkylmethacrylamides having ethyl, propyl, butyl, etc. as an alkylmoiety, and N-hydroxyethyl-N-methylmethacrylamide.

The allyl compounds include allyl esters (e.g., allyl acetate, allylcaproate, allyl caprylate, allyl laurate, allyl palmitate, allylstearate, allyl benzoate, allyl acetoacetate, and allyl lactate) andallyloxyethanol.

The vinyl ethers include alkyl vinyl ethers, such as hexyl vinyl ether,octyl vinyl ether, decyl vinyl ether, ethylhexyl vinyl ether,methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinylether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinylether, hydroxyethyl vinyl ether, diethylene glycol vinyl ether,dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether,butylaminoethyl vinyl ether, benzyl vinyl ether, and tetrahydrofurfurylvinyl ether.

The vinyl esters include vinyl butyrate, vinyl isobutyrate, vinyltrimethylacetate, vinyl diethylacetate, vinyl valerate, vinyl caproate,vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinylbutoxyacetate, vinyl acetoacetate, vinyl lactate, vinylβ-phenylbutyrate, and vinyl cyclohexylcarboxylate.

Further included in the other copolymerizable monomers are dialkylitaconates (e.g., dimethyl itaconate, diethyl itaconate, and dibutylitaconate), dialkyl fumarates (e.g., dibutyl fumarate), monoalkylfumarates, crotonic acid, itaconic acid, maleic anhydride, maleimide,acrylonitrile, methacrylonitrile, and maleonitrile. Any other additionpolymerizable unsaturated compounds that are copolymerizable withmonomers having the above-described various repeating units can be used.

The molar ratio of the repeating units constituting the acid-degradableresin (B) is decided appropriately with due consideration for dryetching resistance, suitability to standard developing solutions,adhesion to a substrate, resist profile, and basic characteristicsrequired of a resist, such as resolution, heat resistance, andsensitivity.

The acid-degradable resin (B) preferably includes the following types.

(B-1) A resin containing a repeating unit having an alicyclichydrocarbon group-containing partial structure represented by formula(pI), (pII), (pIII), (pIV), (pV) or (pVI) (side chain type)

(B-2) A resin containing a repeating unit represented by formula (II-AB)(main chain type)

The main chain type (B-2) includes a resin containing a repeating unitrepresented by formula (II-AB) and having a maleic anhydride derivativestructure and a (meth)acrylate structure (hybrid type).

A preferred content of the repeating unit having an alicyclichydrocarbon group-containing partial structure represented by formula(pI), (pII), (pIII), (pIV), (pV) or (pVI) is 30 to 70 mol %,particularly 35 to 65 mol %, especially 40 to 60 mol %, based on thetotal repeating units.

A preferred content of the repeating unit represented by formula (II-AB)is 10 to 60 mol %, particularly 15 to 55 mol %, especially 20 to 50 mol%, based on the total repeating units.

The contents of other repeating units derived from the above-recitedcopolymerizable monomers are decided appropriately according to desiredresist performance properties. In general, the content of the otherrepeating units is preferably 99 mol % or less, still preferably 90 mol% or less, particularly preferably 80 mol % or less, based on the totalmole number of the repeating unit having the alicyclic hydrocarbongroup-containing partial structure represented by formula (pI), (pII),(pIII), (pIV), (pV) or (pVI) and the repeating unit represented byformula (II-AB).

Where the resist composition of the invention is adapted to be exposedto ArF laser light, it is preferred that the acid-degradable resin (B)be free from an aromatic group to assure transparency to ArF laserlight.

An acid-degradable resin which has a structure containing a fluorineatom substituting the main chain and/or the side chain of the polymerskeleton and decomposes by the action of an acid to increase itssolubility in an alkali developing solution is also preferred ascomponent (B). Such a resin will hereinafter be referred to as afluorine-containing resin. A preferred fluorine-containing resin (B)includes a resin containing at least one fluorine-containing divalentgroup selected from a perfluoroalkylene group and a perfluoroarylenegroup in the main chain thereof and a resin containing, in the sidechain thereof, at least one fluorine-containing monovalent groupselected from a perfluoroalkyl group, a perfluoroaryl group, ahexafluoro-2-propanol group, and a hexafluoro-2-propanol group with itshydroxyl group being protected.

More specifically, the fluorine-containing resin (B) includes resinscontaining at least one of repeating units represented by formulae (I)through (X):

wherein R₀ and R₁ each represent a hydrogen atom, a fluorine atom, asubstituted or unsubstituted alkyl group, a substituted or unsubstitutedperfluoroalkyl group, a substituted or unsubstituted cycloalkyl group ora substituted or unsubstituted aryl group; R₂, R₃, and R₄ each representa substituted or unsubstituted alkyl group, a substituted orunsubstituted perfluoroalkyl group, a substituted or unsubstitutedcycloalkyl group or a substituted or unsubstituted aryl group; R₀ and R₁in formula (I), R₀ and R₂ in formula (II), or R₃ and R₄ in formula (III)may be connected to form a ring; R₅ represents a hydrogen atom, asubstituted or unsubstitutedalkyl group, a substituted or unsubstitutedperfluoroalkyl group, a substituted or unsubstituted monocyclic orpolycyclic cycloalkyl group, a substituted or unsubstituted acyl groupor a substituted or unsubstituted alkoxycarbonyl group; R₆, R₇, and R₈,which may be the same or different, each represent a hydrogen atom, ahalogen atom, a substituted or unsubstituted alkyl group, a substitutedor unsubstituted perfluoroalkyl group or a substituted or unsubstitutedalkoxy group; R₉ and R₁₀, which may be the same or different, eachrepresent a hydrogen atom, a halogen atom, a cyano group, a substitutedor unsubstituted alkyl group or a substituted or unsubstituted haloalkylgroup; R₁₁ and R₁₂, which may be the same or different, each represent ahydrogen atom, a hydroxyl group, a halogen atom, a cyano group, analkoxy group, an acyl group, a substituted or unsubstituted alkyl group,a substituted or unsubstituted cycloalkyl group, a substituted orunsubstituted alkenyl group, a substituted or unsubstituted aralkylgroup or a substituted or unsubstituted aralkyl group; R₁₃ and R₁₄,which may be the same or different, each represent a hydrogen atom, ahalogen atom, a cyano group, a substituted or unsubstituted alkyl groupor a substituted or unsubstituted haloalkyl group; R₁₅ represents afluorine-containing alkyl group, a fluorine-containing monocyclic orpolycyclic cycloalkyl group, a fluorine-containing alkenyl group, afluorine-containing aralkyl group or a fluorine-containing aryl group;R₁₆, R₁₇, and R₁₈, which may be the same or different, each represent ahydrogen atom, a halogen atom, a cyano group, a substituted orunsubstituted alkyl group, a substituted or unsubstituted perfluoroalkylgroup, a substituted or unsubstituted alkoxy group or —CO—O—R₁₅; R₁₉,R₂₀, R₂₁, which may be the same or different, each represent a hydrogenatom, a fluorine atom, a fluorine-containing alkyl group, afluorine-containing monocyclic or polycyclic cycloalkyl group, afluorine-containing alkenyl group, a fluorine-containing aralkyl group,a fluorine-containing aryl group or a fluorine-containing alkoxy group,provided that not all of R₁₉, R₂₀, and R₂₁ represent hydrogen; A₁ and A₂each represent a single bond, a substituted or unsubstituted alkylenegroup, a substituted or unsubstituted alkenylene group, a substituted orunsubstituted cycloalkylene group, a substituted or unsubstitutedarylene group, —O—CO—R₂₂, —CO—O—R₂₃— or —CO—N(R₂₄) —R₂₅—;

-   -   wherein R₂₂, R₂₃, and R₂₅, which maybe the same or different,        each represent a single bond or a divalent group selected from        an alkylene group, an alkenylene group, a cycloalkylene group,        and an arylene group, all of which may have an ether group, an        ester group, an amide group, a urethane group or a ureido group;        R₂₄ represents a hydrogen atom, a substituted or unsubstituted        alkyl group, a substituted or unsubstituted cycloalkyl group, a        substituted or unsubstituted aralkyl group or a substituted or        unsubstituted aryl group;        n represents 0 or 1; and x, y, and z each represent an integer        of 1 to 4.

It is preferred that the acid-degradable fluorine-containing resin (B)further comprise at least one repeating unit represented by formula(XI), (XII) or (XIII):

wherein R₂₆, R₂₇, and R₃₂, which may be the same or different, eachrepresent a hydrogen atom, a halogen atom, a cyano group, a substitutedor unsubstituted alkyl group or a substituted or unsubstituted haloalkylgroup; R₂₈ and R₃₃ each represent —C(R₃₆) (R₃₇) (R₃₈), —C(R₃₆) (R₃₇)(OR₃₉) or a group represented by formula (XIV):

-   -   wherein R₄₀ represents a substituted or unsubstituted alkyl        group, a substituted or unsubstituted cycloalkyl group, a        substituted or unsubstituted alkenyl group, a substituted or        unsubstituted alkynyl group, a substituted or unsubstituted        aralkyl group or a substituted or unsubstituted aryl group; and        Z represents an atomic group necessary to form a monocyclic or        polycyclic alicyclic group together with the adjacent carbon        atom;        R₂₉, R₃₀, and R₃₁, which maybe the same or different, each        represent a hydrogen atom, a halogen atom, a cyano group, a        substituted or unsubstituted alkyl group, a substituted or        unsubstituted perfluoroalkyl group, a substituted or        unsubstituted alkoxy group or —CO—O—R₂₈; R₃₄ and R₃₅, which may        be the same or different, each represent a hydrogen atom, a        hydroxyl group, a halogen atom, a cyano group, an alkoxy group,        an acyl group, a substituted or unsubstituted alkyl group, a        substituted or unsubstituted cycloalkyl group, a substituted or        unsubstituted alkenyl group, a substituted or unsubstituted        aralkyl group or a substituted or unsubstituted aryl group; R₃₆,        R₃₇, R₃₈, and R₃₉, which may be the same or different, each        represent a substituted or unsubstituted alkyl group, a        substituted or unsubstituted cycloalkyl group, a substituted or        unsubstituted alkenyl group, a substituted or unsubstituted        alkynyl group, a substituted or unsubstitutedaralkyl group or a        substituted or unsubstituted aryl group; two of R₃₆, R₃₇, and        R₃₈, or two of R₃₆, R₃₇, and R₃₉ may be connected to form a ring        which may contain an oxo group; A₃ and A₄ each represent a        single bond, a substituted or unsubstituted alkylene group, a        substituted or unsubstituted alkenylene group, a substituted or        unsubstituted cycloalkylene group, a substituted or        unsubstituted arylene group, —O—CO—R₂₂—, —CO—O—R₂₃— or        —CO—N(R₂₄)—R₂₅— (wherein R₂₂, R₂₃, R₂₄, and R₂₅ are as defined        above); and n represents 0 or 1.

For the purpose of controlling hydrophilicity or hydrophobicity, glasstransition point, transparency to exposure light, and like attributes ofthe acid-degradable fluorine-containing resin (B), thefluorine-containing resin (B) may further comprise at least onerepeating unit selected from a maleic anhydride unit represented byformula (XV), a vinyl ether unit represented by formula (XVI), and acyano-containing vinyl compound unit represented by formula (XVII):

wherein R₄₁ represents a substituted or unsubstituted alkyl group, asubstituted or unsubstituted cycloalkyl group, a substituted orunsubstituted aralkyl group or a substituted or unsubstituted arylgroup; R₄₂ represents a hydrogen atom, a cyano group, a substituted orunsubstituted alkyl group or a substituted or unsubstituted haloalkylgroup; A₅ represents a single bond, a substituted or unsubstitutedalkylene group, a substituted or unsubstituted alkenylene group, asubstituted or unsubstituted cycloalkylene group, a substituted orunsubstituted arylene group, —O—CO—R₂₂—, —CO—O—R₂₃— or —CO—N(R₂₄) —R₂₅—(wherein R₂₂, R₂₃, R₂₄, and R₂₅ are as defined above).

Still preferred acid-degradable fluorine-containing resins (B) include aresin comprising at least one repeating unit represented by formula (IA)and at least one repeating unit represented by formula (IIA) and a resincomprising at least one repeating unit represented by formula (IIA) andat least one repeating unit represented by formula (VIA). The resincomprising at least one repeating unit of formula (IA) and at least onerepeating unit of formula (IIA) and the resin comprising at least onerepeating unit of formula (IIA) and at least one repeating unit offormula (VIA) may further comprise the repeating unit represented byformula (I) to (V).

wherein R_(1a) and R_(5a), which may be the same or different, eachrepresent a hydrogen atom, a halogen atom, a cyano group or asubstituted or unsubstituted alkyl group; R_(2a), R_(3a), R_(6a), andR_(7a), which may be the same or different, each represent a hydrogenatom, a halogen atom, a cyano group, a hydroxyl group, a substituted orunsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup, a substituted or unsubstituted alkoxy group, a substituted orunsubstituted acyl group, a substituted or unsubstituted acyloxy group,a substituted or unsubstituted alkenyl group, a substituted orunsubstituted aryl group or a substituted or unsubstituted aralkylgroup; R_(50a), R_(51a), R_(52a), R_(53a), R_(54a), and R_(55a), whichmay be the same or different, each represent a hydrogen atom, a fluorineatom or a substituted or unsubstituted alkyl group, provided that atleast one of R_(50a) to R_(55a) represents a fluorine atom or an alkylgroup with at least one hydrogen atom thereof substituted with afluorine atom; R_(56a) represents a hydrogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup, a substituted or unsubstituted acyl group or a substituted orunsubstituted alkoxycarbonyl group, preferably a hydrogen atom; andR_(4a) represents a group represented by formula (IVA) or (VA):

-   -   wherein R_(11a), R_(12a), and R_(13a), which may be the same or        different, each represent a substituted or unsubstituted alkyl        group, a substituted or unsubstituted cycloalkyl group, a        substituted or unsubstituted alkenyl group, a substituted or        unsubstituted aralkyl group or a substituted or unsubstituted        aryl group; R_(14a) and R_(15a), which may be the same or        different, each represent a hydrogen atom or a substituted or        unsubstituted alkyl group; R_(16a) represents a substituted or        unsubstituted alkyl group, a substituted or unsubstituted        cycloalkyl group, a substituted or unsubstituted aralkyl group        or a substituted or unsubstituted aryl group; and two of        R_(14a), R_(15a), and R_(16a) may be taken together to form a        ring.

wherein R_(17a1) and R_(17a2), which may be the same or different, eachrepresent a hydrogen atom, a halogen atom, a cyano group or asubstituted or unsubstituted alkyl group; R_(18a) represents—C(R_(18a1)) (R_(18a2)) (R_(18a3)) or —C(R_(18a1)) (R_(18a2))(OR_(18a4)); R_(18a1), R_(18a2), R_(18a3), and R_(18a4), which may bethe same or different, each represent a hydrogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup, a substituted or unsubstituted alkenyl group, a substituted orunsubstituted aralkyl group or a substituted or unsubstituted arylgroup; two of R_(18a1), R_(18a2), and R_(18a3) or two of R_(18a1),R_(18a2), and R_(18a4) may be taken together to form a ring; and A₀represents a single bond or a substituted or unsubstituted divalentlinking group, preferably a single bond.

In formula (VIA), R_(18a) is preferably a group represented by formula(VIA-A) or (VIA-B):

wherein R_(18a5) and R_(18a6), which may be the same or different, eachrepresent a substituted or unsubstituted alkyl group; R_(18a7)represents a substituted or unsubstituted cycloalkyl group; and R_(18a8)represents a substituted or unsubstituted alkyl group, a substituted orunsubstituted alkenyl group, a substituted or unsubstituted alkynylgroup, a substituted or unsubstituted aralkyl group or a substituted orunsubstituted aryl group.

It is also preferred that at least one of R_(1a) in formula (IA), R_(5a)in formula (IIA), and R_(17a2) in formula (VIA) be a trifluoromethylgroup.

The resin comprising at least one repeating unit of formula (IA) and atleast one repeating unit of formula (IIA) and the resin comprising atleast one repeating unit of formula (IIA) and at least one repeatingunit of formula (VIA) may further comprise at least one of repeatingunits represented by formulae (IIIA) and (VIIA):

wherein R_(8a) represents a hydrogen atom, a halogen atom, a cyano groupor a substituted or unsubstituted alkyl group; R_(9a) and R_(10a), whichmay be the same or different, each represent a hydrogen atom, a halogenatom, a cyano group, a substituted or unsubstituted alkyl group, asubstituted or unsubstituted cycloalkyl group, a substituted orunsubstituted alkoxy group, a substituted or unsubstituted acyl group, asubstituted or unsubstituted acyloxy group, a substituted orunsubstituted alkenyl group, a substituted or unsubstituted aryl groupor a substituted or unsubstituted aralkyl group; R_(19a) and R_(20a),which may be the same or different, each represent a hydrogen atom, ahalogen atom, a cyano group or a substituted or unsubstituted alkylgroup; R_(21a) represents a hydrogen atom, a halogen atom, a substitutedor unsubstituted alkyl group or -A₁-CN; and A₁ represents a single bondor a divalent linking group.

In the formulae shown above with respect to the fluorine-containingacid-degradable resin (B), the alkyl groups include those having 1 to 8carbon atoms, preferably methyl, ethyl, propyl, n-butyl, sec-butyl,hexyl, 2-ethylhexyl, and octyl. The cycloalkyl groups may be eithermonocyclic or polycyclic. The monocyclic cycloalkyl groups include thosehaving 3 to 8 carbon atoms, preferably including cyclopropyl,cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. The polycycliccycloalkyl groups include those having 6 to 20 carbon atoms, preferablyincluding adamantyl, norbornyl, isobornyl, camphanyl, dicyclopentyl,α-pinenyl, tricyclodecanyl, tetracyclododecyl, and androstanyl. Thecarbon atom of the mono- or polycyclic cycloalkyl groups may bedisplaced with a hetero atom, such as oxygen.

The perfluoroalkyl groups include those having 4 to 12 carbon atoms.Preferred examples are perfluorobutyl, perfluorohexyl, perfluorooctyl,perfluorooctylethyl, and perfluorododecyl. The haloalkyl groups includethose having 1 to 4 carbon atoms, preferably including chloromethyl,chloropropyl, chlorobutyl, bromomethyl, and bromoethyl.

The aryl groups include those having 6 to 15 carbon atoms. Preferredexamples are phenyl, tolyl, dimethylphenyl, 2,4,6-trimethylphenyl,naphthyl, anthryl, and 9,10-dimethoxyanthryl. The aralkyl groups includethose having 7 to 12 carbon atoms. Preferred examples are benzyl,phenethyl, and naphthylmethyl.

The alkenyl groups include those having 2 to 8 carbon atoms. Preferredexamples are vinyl, allyl, butenyl, and cyclohexenyl. The alkoxy groupsinclude those having 1 to 8 carbon atoms. Preferred examples aremethoxy, ethoxy, n-propoxy, isopropoxy, pentoxy, allyloxy, and octoxy.The acyl groups include those having 1 to 10 carbon atoms. Preferredexamples are formyl, acetyl, propanoyl, butanoyl, pivaloyl, octanoyl,and benzoyl. The acyloxy groups preferably include those having 2 to 12carbon atoms, such as acetoxy, propionyloxy, and benzoyloxy.

The alkynyl groups preferably include those having 2 to 5 carbon atoms,such as ethynyl, propynyl, and butynyl. The alkoxycarbonyl groupsinclude isopropoxycarbonyl, t-butoxycarbonyl, t-amyloxycarbonyl, and1-methyl-1-cyclohexyloxycarbonyl, preferably a secondary alkoxycarbonylgroup, still preferably a tertiary one.

The halogen atom includes fluorine, chlorine, bromine, and iodine.

The alkylene groups preferably include substituted or unsubstituted oneshaving 1 to 8 carbon atoms, such as methylene, ethylene, propylene,butylene, hexylene, and octylene. The alkenylene groups preferablyinclude those having 2 to 6 carbon atoms, such as ethenylene,propenylene, and butenylene. The cycloalkylene groups preferably includethose having 5 to 8 carbon atoms, such as cyclopentylene andcyclohexylene. The arylene groups preferably include those having 6 to15 carbon atoms, such as phenylene, tolylene, and naphthylene.

The divalent linking groups include a substituted or unsubstitutedalkylene group, a substituted or unsubstituted cycloalkylene group, asubstituted or unsubstituted alkenylene group, a substituted orunsubstituted arylene group, —O—CO—R_(22a)—, —CO—O—R_(23a)— or—CO—N(R_(24a))—, wherein R_(22a), R_(23a), and R_(25a), which may be thesame or different, each represent a single bond or an alkylene group, analkenylene group, a cycloalkylene group or an arylene group, each ofwhich may contain an ether group, an ester group, an amide group, aurethane group or a ureido group; and R_(24a) represents a hydrogenatom, a substituted or unsubstituted alkyl group, a substituted orunsubstituted cycloalkyl group, a substituted or unsubstituted aralkylgroup or a substituted or unsubstituted aryl group.

The ring formed by R₀ and R₁, the ring formed by Ro and R₂, and the ringformed by R₃ and R₄ include 5- to 7-membered rings, such as pentane,hexane, furan, dioxonol, and 1,3-dioxolane, each of which is substitutedwith fluorine.

The ring formed by two of R₃₆, R₃₇, and R₃₈ and the ring formed by twoof R₃₆, R₃₇, and R₃₉ include 3- to 8-membered rings, such ascyclopropane, cyclopentane, cyclohexane, furan, and pyran.

The ring formed by two of R_(14a), R_(15a), and R_(16a), the ring formedby two of R_(18a1), R_(18a2), and R_(18a3), and the ring formed by twoof R_(18a1), R_(18a2), and R_(18a4) preferably include 3- to 8-memberedrings, such as cyclopropane, cyclopentane, cyclohexane, tetramethyleneoxide, pentamethylene oxide, hexamethylene oxide, furan, pyran,dioxonol, and 1,3-dioxolane.

Z represents an atomic group constituting a monocyclic or polycyclicalicyclic group. The monocyclic alicyclic group formed by Z includes onehaving 3 to 8 carbon atoms, preferably including cyclopropyl,cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. The polycyclicalicyclic group formed by Z includes one having 6 to 20 carbon atoms,preferably including adamantyl, norbornyl, isobornyl, camphanyl,dicyclopentyl, α-pinenyl, tricyclodecanyl, tetracyclododecyl, andandrostanyl.

The substituents that these groups can have include an alkyl group, acycloalkyl group, an aryl group; groups having active hydrogen, such asan amino group, an amide group, a ureido group, a urethane group, ahydroxyl group, and a carboxyl group; a halogen atom (e.g., fluorine,chlorine, bromine or iodine), an alkoxy group (e.g., methoxy, ethoxy,propoxy or butoxy), a thioether group, an acyl group (e.g., acetyl,propanoyl, benzoyl), an acyloxy group (e.g., acetoxy, propanoyloxy orbenzoyloxy), an alkoxycarbonyl group (e.g., methoxycarbonyl,ethoxycarbonyl or propoxycarbonyl), a cyano group, and a nitro group.The alkyl, cycloalkyl and aryl groups include the respective examplesrecited above. The alkyl group may further be substituted with afluorine atom or a cycloalkyl group.

The acid-degradable group, which decomposes in the presence of an acidto become an alkali-soluble group, which is contained in thefluorine-containing resin (B) includes —O—C(R₃₆) (R₃₇) (R₃₈), —O—C(R₃₆)(R₃₇) (OR₃₉), —O—COO—C(R₃₆) (R₃₇) (R₃₈), —O—C(R₀₁) (R₀₂)COO—C(R₃₆) (R₃₇)(R₃₈), —COO—C(R₃₆)(R₃₇ ) (R₃₈), and —COO—C(R₃₆)(R₃₇) (OR₃₉), whereinR₃₆, R₃₇, R₃₈, and R₃₉ are as defined above; and R₀₁ and R₀₂ eachrepresent a hydrogen atom or the above-described substituted orunsubstituted alkyl, cycloalkyl, alkenyl, aralkyl or aryl group.

Examples of preferred acid-degradable groups include ether or estergroups of tertiary alkyl groups, such as t-butyl, t-amyl,1-alkyl-1-cyclohexyl, 2-alkyl-2-adamantyl, 2-adamantyl-2-propyl, and2-(4-methylcyclohexyl)-2-propyl; 1-alkoxy-1-ethoxy groups; acetal oracetal ester groups, such as tetrahydropyranyl; t-alkylcarbonate groups,and t-alkylcarbonylmethoxy groups.

The total content of the repeating units represented by formulae (I) to(X) in the fluorine-containing resin (B) is generally 10 to 80 mol %,preferably 30 to 70 mol %, still preferably 35 to 65 mol %.

The total content of the repeating units represented by formula (XI) to(XIII) in the fluorine-containing resin (B) is generally 0 to 70 mol %,preferably 10 to 60 mol %, still preferably 20 to 50 mol %.

The total content of the repeating units represented by formula (XV) to(XVIII) in the fluorine-containing resin (B) is generally 0 to 70 mol %,preferably 10 to 60 mol %, still preferably 20 to 50 mol %.

The fluorine-containing resin (B) preferably includes a resin comprisingat least one of the repeating units of formulae (I) to (III) and atleast one of the repeating units of formula (IV) to (VI), a resincomprising at least one of the repeating units of formula (IV) to (VI)and at least one of the repeating units of formulae (VIII) to (X), and aresin comprising at least one of the repeating units of formula (IV) to(VII) and at least one of the repeating units of formula (XV) to (XVII).These preferred resins sufficiently increase transparency to light of157 nm and suppress reduction of dry etching resistance.

The resin comprising at least one of the repeating units of formulae (I)to (III) and at least one of the repeating units of formula (IV) to (VI)usually has a total content of the former units of 0 to 70 mol %,preferably 10 to 60 mol %, still preferably 20 to 50 mol %, and a totalcontent of the latter units of 10 to 80 mol %, preferably 30 to 70 mol%, still preferably 35 to 65 mol %.

The resin comprising at least one of the repeating units of formula (IV)to (VI) and at least one of the repeating units of formulae (VIII) to(X) usually has a total content of the former units of 10 to 80 mol %,preferably 30 to 70 mol %, still preferably 35 to 65 mol %, and a totalcontent of the latter units of 0 to 70 mol %, preferably 10 to 60 mol %,still preferably 20 to 50 mol %.

The resin comprising at least one of the repeating units of formula (IV)to (VII) and at least one of the repeating units of formula (XV) to(XVII) usually has a total content of the former units of 10 to 80 mol%, preferably 30 to 70 mol %, still preferably 35 to 65 mol %, and atotal content of the latter units of 0 to 70 mol %, preferably 10 to 60mol %, still preferably 20 to 50 mol %.

The resin comprising at least one of the repeating units of formula (IA)and at least one of the repeating units of formula (IIA) usually has atotal content of the repeating units of formula (IA) of 5 to 80 mol %,preferably 10 to 75 mol %, still preferably 20 to 70 mol %, and a totalcontent of the repeating units of formula (IIA) of 5 to 80 mol %,preferably 10 to 70 mol %, still preferably 20 to 65 mol %.

The resin comprising at least one of the repeating units of formula(IIA) and at least one of the repeating units of formula (VIA) usuallyhas a total content of the repeating units of formula (IIA) of 5 to 80mol %, preferably 10 to 70 mol %, still preferably 20 to 65 mol %, and atotal content of the repeating units of formula (VIA) of 5 to 80 mol %,preferably 10 to 70 mol %, still preferably 20 to 65 mol %.

The content of the repeating unit of formula (IIIA) in these resins isusually 1 to 40 mol %, preferably 3 to 35 mol %, still preferably 5 to30 mol %. The content of the repeating unit of formula (VIIA) in theseresins is usually 1 to 40 mol %, preferably 3 to 35 mol %, stillpreferably 5 to 30 mol %.

The acid-degradable fluorine-containing resin (B) may further comprisevarious repeating units other than those described above for the purposeof improving resist performance. Useful comonomers providing the otherrepeating units include compounds having one addition polymerizableunsaturated bond, such as acrylic esters, acrylamides, methacrylicesters, methacrylamides, allyl compounds, vinyl ethers, vinyl esters,styrenes, and crotonic esters.

The acrylic esters include alkyl esters, preferably those having 1 to 10carbon atoms in the alkyl moiety and aryl esters. Examples of the alkylesters are methyl acrylate, ethyl acrylate, propyl acrylate, t-butylacrylate, amyl acrylate, cyclohexyl acrylate, ethylhexyl acrylate, octylacrylate, t-octyl acrylate, chloroethyl acrylate, 2-hydroxyethylacrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate,trimethylolpropane monoacrylate, pentaerythritol monoacrylate, glycidylacrylate, benzyl acrylate, furfuryl acrylate, and tetrahydrofurfurylacrylate. Examples of the aryl esters include phenyl acrylate.

The methacrylic esters include alkyl esters, preferably those having 1to 10 carbon atoms in the alkyl moiety and aryl esters. Examples of thealkyl esters are methyl methacrylate, ethyl methacrylate, propylmethacrylate, isopropyl methacrylate, t-butyl methacrylate, amylmethacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzylmethacrylate, chlorobenzyl methacrylate, octyl methacrylate,2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate,5-hydroxypentyl methacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate,trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate,glycidylmethacrylate, furfurylmethacrylate, and tetrahydrofurfurylmethacrylate. Examples of the aryl esters are phenyl methacrylate,cresyl methacrylate, and naphthyl methacrylate.

The acrylamides include acrylamide, N-alkylacrylamides having an alkylmoiety containing 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl,butyl, t-butyl, heptyl, octyl, cyclohexyl, benzyl or hydroxyethyl),N-arylacrylamides having phenyl, tolyl, nitrophenyl, naphthyl,cyanophenyl, hydroxyphenyl, carboxyphenyl, etc. as an aryl moiety,N,N-dialkylacrylamides having an alkyl group containing 1 to 10 carbonatoms (e.g., methyl, ethyl, butyl, isobutyl, ethylhexyl or cyclohexyl),N,N-diarylacrylamides having, e.g., phenyl as an aryl moiety,N-methyl-N-phenylacrylamide, N-hydroxyethyl-N-methylacrylamide, andN-2-acetamidoethyl-N-acetylacrylamide.

The methacrylamides include methacrylamide, N-alkylmethacrylamideshaving an alkyl moiety containing 1 to 10 carbon atoms (e.g., methyl,ethyl, t-butyl, ethylhexyl, hydroxyethyl or cyclohexyl),N-arylmethacrylamides having, e.g., phenyl as an aryl moiety,N,N-dialkylmethacrylamides having ethyl, propyl, butyl, etc. as an alkylmoiety, N,N-diarylmethacrylamides having phenyl, etc. as an aryl moiety,N-hydroxyethyl-N-methylmethacrylamide, N-methyl-N-phenylmethacrylamide,and N-ethyl-N-phenylmethacrylamide.

The allyl compounds include allyl esters (e.g., allyl acetate, allylcaproate, allyl caprylate, allyl laurate, allyl palmitate, allylstearate, allyl benzoate, allyl acetoacetate, and allyl lactate) andallyloxyethanol.

The vinyl ethers include alkyl vinyl ethers, such as hexyl vinyl ether,octyl vinyl ether, decyl vinyl ether, ethylhexyl vinyl ether,methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinylether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinylether, hydroxyethyl vinyl ether, diethylene glycol vinyl ether,dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether,butylaminoethyl vinyl ether, benzyl vinyl ether, and tetrahydrofurfurylvinyl ether; and aryl vinyl ethers, such as phenyl vinyl ether, tolylvinyl ether, chlorophenyl vinyl ether, 2,4-dichlorophenyl vinyl ether,naphthyl vinyl ether, and anthranyl vinyl ether.

The vinyl esters include vinyl butyrate, vinyl isobutyrate, vinyltrimethylacetate, vinyl diethylacetate, vinyl valerate, vinyl caproate,vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinylbutoxyacetate, vinyl phenylacetate, vinyl acetoacetate, vinyl lactate,vinyl β-phenylbutyrate, vinyl cyclohexylcarboxylate, vinyl benzoate,vinyl salicylate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, andvinyl naphthoate.

The styrenes include styrene; alkylstyrenes, such as methylstyrene,dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene,isopropylstyrene, butylstyrene, hexylstyrene, cyclohexylstyrene,decylstyrene, benzylstyrene, chloromethylstyrene,trifluoromethylstyrene, ethoxymethylstyrene, andacetoxymethylstyrene;alkoxystyrenes, such as methoxystyrene, 4-methoxy-3-methylstyrene, anddimethoxystyrene; halogenostyrenes, such as chlorostyrene,dichlorostyrene, trichlorostyrene, tetrachlorostyrene,pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene,fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, and4-fluoro-3-trifluoromethylstyrene; carboxystyrene; and vinylnaphthalene.

The crotonic esters include alkyl crotonates, such as butyl crotonate,hexyl crotonate, and glycerol monocrotonate.

Further included in the other copolymerizable monomers are dialkylitaconates (e.g., dimethyl itaconate, diethyl itaconate, and dibutylitaconate), dialkyl fumarates (e.g., dibutyl fumarate), dialkyl maleates(e.g., dimethyl maleate), maleic anhydride, maleimide, acrylonitrile,methacrylonitrile, and maleonitrile. Any other addition polymerizableunsaturated compounds that are copolymerizable with monomers having theabove-described various repeating units can be used.

Specific but non-limiting examples of the repeating units represented byformulae (I) to (X) are shown below.

Specific but non-limiting examples of the repeating units represented byformulae (XI) to (XIII) are shown below.

Specific but non-limiting examples of the repeating units represented byformulae (XVI) to (XVII) are shown below.

Specific but non-limiting examples of the repeating units represented byformula (IA) are shown below.

Specific but non-limiting examples of the repeating units represented byformula (IIA) are shown below.

Additionally, repeating units (F-40) through (F-45) shown above are alsoincluded in the repeating units of formula (IIA).

Specific but non-limiting examples of the repeating units represented byformula (VIA) are shown below.

Additionally, repeating units (F-29) through (F-38) and (F-47) through(F-54) shown above are also included in the repeating units of formula(VIA).

Specific but non-limiting examples of the repeating units represented byformula (IIIA) are shown below.

Specific but non-limiting examples of the repeating units represented byformula (VIIA) are shown below.

The acid-degradable resin (B) which can be used in the invention issynthesized in a usual manner, for example, by radical polymerization.General radical polymerization is carried out as follows. All themonomers are put into a reaction vessel at once, or some monomers may beadded during reaction. If desired, a reaction solvent capable ofdissolving the monomer mixture and the composition of the presentinvention is added to uniformly dissolve the monomer mixture. Usefulreaction solvents include ethers, such as tetrahydrofuran, 1,4-dioxane,and diisopropyl ether; ketones, such as methyl ethyl ketone and methylisobutyl ketone; esters, such as ethyl acetate; and propylene glycolmonomethyl ether acetate. A commercially available radical initiator,such as an azo initiator or a peroxide, is added to the system toconduct polymerization of the monomers in an inert gas (e.g., nitrogenor argon) atmosphere under, if necessary, heating. If desired, anadditional amount of the initiator can be added later, or the initiatorcan be added in divided portions. After completion of the reaction, thereaction system is poured into a poor solvent, and the polymer producedis collected in the form of powder or solid. The reaction systemconcentration is at least 20% by weight, preferably 30% by weight orhigher, still preferably 40% by weight or higher. The reactiontemperature ranges 10 to 150° C., preferably 30 to 120° C., stillpreferably 50 to 100° C.

The number of the kinds of repeating units represented by a singleformula shown above which are used to make up the acid-degradable resin(B) may be one or more than one. The above-described acid-degradableresins (A) may be used either individually or as a combination of two ormore thereof.

The weight average molecular weight (Mw) of the resin (B) is preferably1,000 to 200,000, still preferably 3,000 to 20,000, in terms ofpolystyrene equivalent Mw determined by gel-permeation chromatography(GPC). With Mw less than 1,000, the resist tends to have reduced heatresistance or reduced dry etching resistance. With Mw more than 200,000,the resist tends to have reduced developability, or the composition willhave too high a viscosity, which can result in poor film-formingproperties.

The molecular weight distribution of the resin (B) is preferably in arange of 1 to 10, still preferably 1 to 5, particularly preferably 1 to4. The smaller the molecular weight distribution, the higher the resistperformance, such as resolution, resist profile, smoothness of resistpattern side walls, and LER.

The total resin content of the positive resist composition of theinvention preferably ranges from 40 to 99.99% by weight, particularly 50to 99.97% by weight, on solid basis.

The positive resist composition of the present invention comprises anacyclic compound having at least three groups selected from a hydroxylgroup and a substituted hydroxyl group as component (D) (hereinafterreferred to as compound (D)). Compound (D) is preferably an acyclicsaccharide derivative having at least three groups selected from ahydroxyl group and a substituted hydroxyl group. The “acyclic saccharidederivative having at least three groups selected from a hydroxyl groupand a substituted hydroxyl group” includes ring-opened structures ofgeneral saccharides and analogues thereof.

Such compounds include, but are not limited to, threitol, erythritol,adonitol, arabitol, xylitol, sorbitol, mannitol, iditol, dulcitol,erythrol, xylulose, ribulose, deoxyribulose, glucero-gulo-heptose, andthe compounds shown below:

Some of these acyclic saccharide derivatives have optical isomers, allof which are included in component (D). The hydroxyl groups of thesecompounds may be substituted with an acid-degradable group, such as anacetal group and an isopropylidene group, or other substituents.

The number of hydroxyl groups and/or substituted hydroxyl groups in thecompound (D) is preferably 3 to 10, still preferably 4 to 10. Presenceof more than 10 hydroxyl groups and/or substituted hydroxyl groups permolecule tends to result in considerable film thickness reduction.

The compounds (D) can be used either individually or as a mixture of twoor more thereof as component (D). Component (D) is usually used in anamount of 0.001 to 10% by weight, preferably 0.01 to 5% by weight, basedon the solids content of the positive resist composition. Addition ofless than 0.001% of component (D) produces no substantial effect.Addition of more than 10% of component (D) tends to result in reductionof sensitivity or developability of exposed areas.

It is preferred for the positive resist composition of the invention tofurther comprise (C) a basic compound. The basic compound as component(C) includes nitrogen-containing basic compounds. Nitrogen-containingbasic compounds include those which do not cause deterioration ofsublimating properties and resist performance, such as organic amines,basic ammonium salts, and basic sulfonium salts. Organic amines arepreferred of them for excellent imaging performance. Useful organicamines are described, e.g., in JP-A-63-149640, JP-A-5-249662,JP-A-5-127369, JP-A-5-289322, JP-A-5-249683, JP-A-5-289340,JP-A-5-232706, JP-A-5-257282, JP-A-6-242605, JP-A-6-242606,JP-A-6-266100, JP-A-6-266110, JP-A-6-317902, JP-A-7-120929,JP-A-7-146558, JP-A-7-319163, JP-A-7-508840, JP-A-7-333844,JP-A-7-219217, JP-A-7-92678, JP-A-7-28247, JP-A-8-22120, JP-A-8-110638,JP-A-8-123030, JP-A-9-274312, JP-A-9-166871, JP-A-9-292708,JP-A-9-325496, JP-T-508840, U.S. Pat. Nos. 5,525,453, 5,629,134, and5,667,938.

Specifically, the nitrogen-containing basic compounds preferably includethose represented by structures (A) to (E):

wherein R²⁵⁰, R²⁵¹, and R²¹², which may be the same or different, eachrepresent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms,an aminoalkyl group having 1 to 20 carbon atoms, a hydroxyalkyl grouphaving 1 to 20 carbon atoms or a substituted or unsubstituted aryl grouphaving 6 to 20 carbon atoms; R²⁵¹ and R²⁵² may be taken together to forma ring; R²⁵³, R²⁵⁴, R²⁵⁵, and R²⁵⁶, which may be the same or different,each represent an alkyl group having 1 to 10 carbon atoms.

Still preferred nitrogen-containing basic compounds include those havingtwo or more nitrogen atoms in different chemical environments permolecule and aliphatic tertiary amines.

Examples of preferred nitrogen-containing basic compounds are1,5-diazabicyclo[4.3.0]-5-nonene, 1,8-diazabicyclo[5.4.0]-7-undecene,1,4-diazabicyclo[2,2,2]octane, 4-dimethylaminopyridine, 1-naphthylamine,piperidines, hexamethylenetetramine, imdiazoles, hydroxypyridines,pyridines, anilines, hydroxyalkylanilines, 4,4′-diaminodiphenyl ether,pyridinium p-toluenesulfonate, 2,4,6-trimethylpyridiniump-toluenesulfonate, tetramethylammonium p-toluenesulfonate,tetrabutylammonium lactate, triethylamine, tributylamine,tripentylamine, tri-n-octylamine, tri-isooctylamine,tris(ethylhexyl)amine, tridecylamine, and tridodecylamine. Particularlypreferred of them are organic amines, such as1,5-diazabicyclo[4.3.0]-5-nonene, 1,8-diazabicyclo[5.4.0]-7-undecene,1,4-diazabicyclo[2.2.2]octane, 4-dimethylaminopyridine, 1-naphthylamine,piperidine, 4-hydroxypiperidine,2,2,6,6-tetramethyl-4-hydroxypiperidine, hexamethylenetetramine,imidazoles, hydroxypyridine, pyridines, 4,4′-diaminidiphenyl ether,triethylamine, tributylamine, tripentylamine, tri-n-octylamine,tris(ethylhexyl)amine, tridodecylamine, N,N-dihydroxyethylaniline, andN-hydroxyethyl-N-ethylaniline.

The basic compounds can be used either individually or as a combinationof two or more thereof. The basic compounds are usually used in a totalamount of 0.001 to 10% by weight, preferably 0.01 to 5% by weight, basedon the solids content of the resist composition. When added in totalamounts less than 0.001%, the effects of addition are insubstantial.Total amounts more than 10% can result in reduction of sensitivity ordevelopability of exposed areas.

It is preferred for the positive resist composition of the presentinvention to further comprise (E) at least one of a fluorine-containingsurface active agent, a silicon-containing surface active agent, and asurface active agent containing both fluorine and silicon. Incorporationof component (E) is effective to form a resist pattern having goodadhesion to a substrate and free from development defects with highsensitivity and high resolution when in using an exposure source of 250nm or shorter wavelengths, particularly 220 nm or shorter.

Examples of the fluorine- and/or silicon-containing surface activeagents are described, e.g., in JP-A-62-36663, JP-A-61-226746,JP-A-61-226745, JP-A-62-170950, JP-A-63-34540, JP-A-7-230165,JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, and U.S. Pat. Nos. 5,405,720,5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511, and5,824,451. Commercially available fluorine- and/or silicon-containingsurface active agents which can be used in the present invention includeEFTOP series EF301 and EF303 (from Shin Akita Kasei K.K.); Fluoradseries FC430 and FC431 (from Sumitomo 3M Ltd.); Megafac series F171,F173, F176, F189, and R08 (from Dainippon Ink & Chemicals Inc.); Surflonseries S-382, SC101, 102, 103, 104, 105 and 106 (from Asahi Glass Co.,Ltd.); and Troy Sol S-366 (from Troy Chemical Industries, Inc.).Polysiloxane resin KP-341 (from Shin-Etsu Chemical Co., Ltd.) is alsouseful as a silicon-containing surface active agent.

Component (E) is used in an amount of 0.0001 to 2% by weight, preferably0.001 to 1% by weight, based on the total resist composition except asolvent.

The positive resist composition of the present invention is used asdissolved in an appropriate organic solvent. Suitable solvents includeethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone,γ-butyrolactone, methyl ethyl ketone, ethylene glycol monomethyl ether,ethylene glycol monoethyl ether, 2-methoxyethyl acetate, ethylene glycolmonoethyl ether acetate, propylene glycol monomethyl ether, propyleneglycol monomethyl ether acetate, toluene, ethyl acetate, methyl lactate,ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, methylpyruvate, ethyl pyruvate, propyl pyruvate, N,N-dimethylformamide,dimethyl sulfoxide, N-methylpyrrolidone, and tetrahydrofuran.

In the present invention, it is preferred to use a mixed solventcomprising a solvent having a hydroxyl group in its structure and asolvent containing no hydroxyl group thereby to suppress particlegeneration during storage of the resist composition.

Solvents containing a hydroxyl group include ethylene glycol, ethyleneglycol monomethyl ether, ethylene glycol monoethyl ether, propyleneglycol, propylene glycol monomethyl ether, propylene glycol monoethylether, and ethyl lactate. Propylene glycol monomethyl ether and ethyllactate are preferred of them.

Solvents containing no hydroxyl group include propylene glycolmonomethyl ether acetate, ethyl ethoxypropionate, 2-heptanone,γ-butyrolactone, cyclohexanone, butyl acetate, N-methylpyrrolidone,N,N-dimethylacetamide, and dimethyl sulfoxide. Preferred of them arepropylene glycol monomethyl ether acetate, ethyl ethoxypropionate,2-heptanone, γ-butyrolactone, cyclohexanone, and butyl acetate.Propylene glycol monomethyl ether acetate, ethyl ethoxypropionate, and2-heptanone are particularly preferred.

A mixing weight ratio of the solvent containing a hydroxyl group to thesolvent containing no hydroxyl group is usually 1/99 to 99/1, preferably10/90 to 90/10, still preferably 20/80 to 60/40. A mixed solventcontaining at least 50% by weight of the solvent with no hydroxyl groupis desirable for achieving coating uniformity.

The positive resist composition of the present invention can furthercomprise (G) a resin which contains no acid-degradable group and isinsoluble in water but soluble in an alkali developing solution therebyto have improved sensitivity. Resins useful as component (G) includenovonak resins having molecular weights of about 1,000 to 20,000 andpolyhydroxystyrene resins having molecular weights of about 3,000 to50,000. Because these resins have a large absorption at 250 nm orshorter wavelengths, they are preferably hydrogenated partially, ortheir amounts are preferably limited to 30% by weight at the most basedon the total resin.

A resin having a carboxyl group as an alkali-soluble group can also beused in combination. The carboxyl-containing resin preferably contains amonocyclic or polycyclic alicyclic hydrocarbon group for improving dryetching resistance. Such a carboxyl-containing resin includesmethacrylic ester-(meth)acrylic acid copolymers containing anacid-non-degradable alicyclic hydrocarbon structure and (meth) acrylicester resins containing an alicyclic hydrocarbon group having a carboxylend group.

The positive resist composition of the present invention can containvarious additives according to necessity, such as dyes, plasticizers,surface active agents other than those described above as component (E),photosensitizers, and compounds accelerating dissolution in a developingsolution.

The compounds which can be added for the purpose of acceleratingdissolution in a developing solution include low-molecular (molecularweight: 1,000 or less) compounds containing two or more phenolichydroxyl groups or one or more carboxyl groups per molecule. Thecarboxyl-containing compounds are preferably alicyclic or aliphaticcompounds for the same reason as described above.

The compound accelerating dissolution in a developing solution ispreferably added in an amount of 2 to 50% by weight, particularly 5 to30% by weight, based on the resin (B). Where added in amounts exceeding50% by weight, the development residue deteriorates, and the pattern isdeformed during development.

The phenolic compounds having molecular weights of 1,000 or less caneasily be synthesized by those skilled in the art by referring to theprocesses described in JP-A-4-122938, JP-A-2-28531, U.S. Pat. No.4,916,210, and EP 219294.

The alicyclic or aliphatic compounds having a carboxyl group include,but are not limited to, carboxylic acid derivatives having a steroidstructure, such as cholic acid, deoxycholic acid, and lithocholic acid,adamantanecarboxylic acid derivatives, adamantanedicarboxylic acid,cyclohexanecarboxylic acid, and cyclohexanedicarboxylic acid.

In addition to the fluorine- and/or silicon-containing surface activeagent as component (E), the resist composition can contain other surfaceactive agents, such as nonionic surface active agents. Suitable nonionicsurface active agents include polyoxyethylene alkyl ethers, e.g.,polyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether;polyoxyethylene alkylaryl ethers, e.g., polyoxyethylene octylphenylether and polyoxyethylene nonylphenyl ether; ethylene oxide-propyleneoxide block copolymers; sorbitan fatty acid esters, e.g., sorbitanmonolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitanmonooleate, sorbitan trioleate, and sorbitan tristearate;polyoxyethylene sorbitan fatty acid esters, e.g., polyoxyethylenesorbitan monolaurate, polyoxyethylene sorbitan monopalmitate,polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitantrioleate, and polyoxyethylene sorbitan tristearate. These surfaceactive agents can be used either individually or as a combinationthereof.

The positive resist composition of the invention is dissolved in anappropriate solvent, preferably the above-described mixed solvent toprepare a coating composition, which is applied to a substrate. Thecoating composition is applied to a substrate, such as a siliconesubstrate with a silicon dioxide coat, by means of an appropriatecoating unit, such as a spinner or a coater, to form a resist film. Theresist film is exposed to light through a prescribed mask. Afterpost-exposure baking, the resist is developed with an alkali developingsolution to remove the exposed area. The light of exposure preferablyhas a wavelength of 250 nm or shorter, particularly 220 nm or shorter.Suitable light includes KrF excimer laser light (248 nm), ArF excimerlaser light (193 nm), F₂ excimer laser light (157 nm), X-rays, and anelectron beam.

The alkali developing solution includes aqueous alkali solutions. Thealkali includes inorganic alkalis, such as sodium hydroxide, potassiumhydroxide, sodium carbonate, sodium silicate, sodium metasilicate, andaqueous ammonia; primary amines, such as ethylamine and n-propylamine;secondary amines, such as diethylamine and di-n-butylamine; tertiaryamines, such as triethylamine and methyldiethylamine; alcohol amines,such as dimethylethanolamine and triethanolamine; quaternary ammoniumsalts, such as tetramethylammonium hydroxide and tetraethylammoniumhydroxide; and cyclic amines, such as pyrrole and piperidine. Theaqueous alkali solution may contain an adequate amount of an alcohol ora surface active agent.

EXAMPLES

The present invention will now be illustrated in greater detail withreference to Examples, but it should be understood that the invention isby no means limited thereto.

Synthesis Example 1

Synthesis of Resin (1) (Side Chain Type):

2-Ethyl-2-adamantyl methacrylate and butyrolactone methacrylate were putinto a reaction vessel in a molar ratio of 55/45 and dissolved in a 5/5(by weight) mixed solvent of methyl ethyl ketone (MEK) andtetrahydrofuran (THF) to prepare 100 ml of a 20 wt % monomer solution.

2,2′-Azobis (2,4-dimethylvaleronitrile) (V-65, available from Wako PureChemical Industries, Ltd.) was added as a polymerization initiator in anamount of 2 mol % based on the total monomers. The resulting mixture wasadded dropwise to 10 ml of MEK heated to 60° C. over 4 hours in anitrogen atmosphere. After the addition, the reaction mixture was heatedfor 4 hours. One molar percent of V-65 was added to the reaction system,followed by stirring for 4 hours. After completion of the reaction, thereaction mixture was cooled to room temperature and poured into 3 litersof a 1/1 mixture of distilled water and isopropyl alcohol to precipitatewhite powder, which was collected to recover resin (1).

As a result of C¹³-NMR analysis, the copolymerization ratio of2-ethyl-2-adamantyl methacrylate to butyrolactone methacrylate was foundto be 46/54. GPC analysis revealed that resin (1) had a polystyreneequivalent weight average molecular weight (Mw) of 10,700.

Resins (2) to (12) were synthesized in the same manner as for resin (1).The copolymerization ratios and the molecular weights of resins (2) to(12) are shown in Table 1 below, in which the order of the repeatingunits from left to right is the same as that in the structural formulashown below.

TABLE 1 1st Unit 2nd Unit 3rd Unit 4th Unit Resin (mol %) (mol %) (mol%) (mol %) Mw 2 53 40 7 13400 3 42 31 27 8300 4 42 30 28 10300 5 39 3526 8900 6 46 22 30 2 12900 7 38 32 30 11300 8 38 31 29 2 11100 9 35 6 1643 13200 10 46 42 12 9200 11 38 32 30 11300 12 42 18 38 2 13800

The structures of resins (1) to (12) were as shown below.

Synthesis Example 2

Synthesis of Resin (13) (Main Chain Type):

t-Butyl norbornenecarboxylate, butyrolactone norbornenecarboxylate, andmaleic anhydride (40/10/50 by mole) and THF were put into a separableflask (solids content of the mixture: 60 wt %), and the mixture washeated at 60° C. in a nitrogen stream. When a steady reactiontemperature was reached, 2 mol % of a radical initiator V-601 (from WakoPure Chemical) based on the total monomers was added to commencepolymerization. The reaction was continued for 12 hours by heating. Theresulting reaction mixture was diluted twice with THF and poured into a1/1 mixture of hexane/isopropyl alcohol. The precipitated white powerwas collected by filtration and dried to obtain resin (13).

The polystyrene equivalent weight average molecular weight of resin (13)measured by GPC was 8300. The NMR analysis revealed that thecopolymerization ratio of b-butylnorbornenecarboxylate/norbornenecarboxylic acid butyrolactoneester/maleic anhydride was 42/8/50.

Resins (14) to (17) were synthesized in the same manner as for resin(13). The composition and the molecular weight of resins (14) to (17)are shown in Table 2 below, in which the order of the repeating unitsfrom left to right is the same as that in the structural formula.

TABLE 2 1st Unit*¹ 2nd Unit*² 3rd Unit*³ Resin (mol %) (mol %) (mol %)Mw 14 35 15 50 8200 15 31 19 50 7900 16 38 12 50 8900 17 40 10 50 9300*1: Alicyclic olefin unit *2: Alicyclic olefin unit *3: Maleic anhydrideunit

The structures of resins (13) to (17) are shown below.

Synthesis Example 3

Synthesis of Resin (18) (Hybrid Type):

Norbornene, maleic anhydride, t-butyl acrylate, and2-methylcyclohexyl-2-propyl acrylate were put into a reaction vessel ata molar ratio of 35/35/20/10 and dissolved in THF to prepare a 60%monomer solution. The solution was heated to 65° C. in a nitrogenstream. When a steady reaction temperature was reached, 1 mol %, basedon the total monomers, of a radical initiator V-601 (from Wako PureChemical) was added to commence polymerization. After heating for 8hours, the reaction mixture was diluted with a 2-fold volume of THF andpoured into a 5-fold volume of hexane. The precipitated white powder wascollected by filtration, dissolved in MEK, and re-precipitated in a5-fold volume of a 1/1 mixture of hexane and t-butyl methyl ether. Theprecipitated white powder was collected by filtration and dried to giveresin (18).

As a result of NMR analysis, the copolymerization ratio ofnorbornene/maleic anhydride/t-butyl acrylate/2-methylcyclohexyl-2-propylacrylate was found to be 32/39/19/10 by mole. GPC analysis revealed thatresin (18) had a polystyrene equivalent weight average molecular weight(Mw) of 12100.

Resins (19) to (24) were synthesized in the same manner as for resin(18). The copolymerization ratios and the molecular weights of resins(19) to (24) are shown in Table 3 below.

TABLE 3 Acid Norbornene Anhydride (Meth)-acrylate Resin Unit (mol %)Unit (mol %) Unit(s) (mol %) Mw 19 16 21 36/27 13900 20 15 22 34/2912300 21 18 24 32/26 13000 22 15 20 29/10/26 13100 23 20 22 58 14700 2423 28 35/14 13300

The structures of resins (18) to (24) are shown below.

Synthesis Example 4

Synthesis of Resin (25) (Hybrid Type):

t-Butyl norbornenecarboxylate, maleic anhydride, 2-methyl-2-adamantylacrylate, and norbornene lactone acrylate were put into a reactionvessel at a molar ratio of 20/20/35/25 and dissolved in a 1/1 (byweight) mixed solvent of MEK and THF to prepare a 60% monomer solution.The solution was heated to 65° C. in a nitrogen stream. When a steadyreaction temperature was reached, 3 mol %, based on the total monomers,of a radical initiator V-601 (from Wako Pure Chemical) was added tocommence polymerization. After heating for 12 hours, the reactionmixture was poured into a 5-fold volume of hexane. The precipitatedwhite powder was again dissolved in a 1/1 (by weight) mixed solvent ofMEK/THF, and re-precipitated in a 5-fold volume of a 1/1 mixture ofhexane and t-butyl methyl ether. The precipitated white powder wascollected by filtration. These purification operations were repeated,and the collected precipitate was dried to obtain resin (25).

As a result of NMR analysis, the copolymerization ratio ofnorbornene/maleic anhydride/2-methyl-2-adamantyl acrylate/norbornenelactone acrylate was found to be 18/23/34/25 by mole. GPC analysis (RIanalysis) revealed that resin (25) had a polystyrene equivalent weightaverage molecular weight (Mw) of 11600.

Resins (26) to (31) were synthesized in the same manner as for resin(25). The copolymerization ratios and the molecular weights of resins(26) to (31) are shown in Table 4 below.

TABLE 4 Norbornene Acid Acrylate Unit(s) Anhydride Unit(s) Resin (mol %)Unit (mol %) (mol %) Mw 26 24 29 31/16 12300 27 31 35 21/13 9200 2830/6  42 22 7700 29 38 42 15/5  9300 30 19 24 40/17 9500 31 29 32 34/5 10400

The structures of resins (25) to (31) are shown below.

Synthesis Example 5

Synthesis of Resin (F1):

In a one-liter autoclave was charged a solution of 9.4 g (0.10 mol) ofnorbornene and 19.4 g (0.10 mol) of t-butyl norbornene-2-carboxylate in150 ml of 1,1,2-trichlorotrifluoroethylene, and the autoclave waspressurized to 200 psi with nitrogen. To the mixture was added 20 g(0.20 mol) of tetrafluoroethylene, and the mixture was heated to 50° C.while stirring. A solution of 1.2 g of di(4-t-butylcyclohexyl)peroxydicarboxylate in 15 ml of 1,1,2-trichlorotrifluoroethylene wasadded to the reaction mixture over 20 minutes, followed by stirring foran additional 20 hour period. After completion of the reaction, thereaction mixture was poured into 2 liters of methanol with vigorousstirring. The precipitated white resin was collected by filtration anddried in vacuo to give 23.5 g of resin (F1).

As a result of GPC analysis, resin (F1) had a weight average molecularweight (Mw) of 6,200. C¹³-NMR analysis revealed that the composition ofresin (F1) was (F-1)/norbornene/(B-16)=45/30/25 by mole.

Synthesis Example 6

Synthesis of Resin (F2):

In 100 ml of MEK were dissolved 14.3 g (0.04 mol) of monomer (a) shownbelow, 3.9 g (0.04 mol) of maleic anhydride, and 2.6 g (0.02 mol) oft-butyl acrylate, and the solution was heated to 70° C. in a nitrogenstream. A 0.2 g portion of a polymerization initiator V-601 (from WakoPure Chemical) was added to the mixture, followed by stirring for 3hours. An additional 0.2 g portion of V-601 was added, and stirring wascontinued for 4 hours. The reaction mixture was poured into 1 liter ofmethyl t-butyl ether with vigorous stirring to precipitate a whiteresin, which was collected by filtration and dried in vacuo to give 12.1g of resin (F2).

As a result of GPC analysis, resin (F2) had a weight average molecularweight (Mw) of 8,900. C¹³-NMR analysis revealed that the composition ofresin (F2) was (F-21)/maleic anhydride/(B-4)=39/38/23 by mole.

Monomer (a):

Synthesis Example 7

Synthesis of Resin (F3):

In 30 ml of 1-methoxy-2-propanol were dissolved 6.7 g (0.015 mol) ofmonomer (b) shown below, 1.4 g (0.006 mol) of 2-methyl-2-adamantylmethacrylate, and 1.8 g (0.009 mol) of mevalonic lactone methacrylate. Asolution of 0.1 g of a polymerization initiator V-65 (from Wako PureChemical), 15.6 g (0.035 mol) of monomer (b), 3.3 g (0.014 mol) of2-methyl-2-adamantyl methacrylate, and 4.2 g (0.021 mol) of mevaloniclactonemethacrylate in 70 ml of 1-methoxy-2-propanol was added dropwiseto the solution at 70° C. over 2 hours in a nitrogen stream whilestirring. After the dropwise addition, additional 0.1 g of the initiatorwas added to the mixture, followed by stirring for 2 hours. The reactiontemperature was raised to 90° C., at which the stirring was continuedfor an additional 1 hour period. The reaction mixture was allowed tocool and then poured into 1 liter of a 1/1 mixture of ion-exchangedwater and methanol with vigorous stirring to precipitate a white resin,which was collected by filtration and dried under reduced pressure togive 15.8 g of resin (F3).

As a result of GPC analysis, resin (F3) had a weight average molecularweight (Mw) of 10,200. C¹³-NMR analysis revealed that resin (F3) had acomposition of (F-30)/(B-7)/(B-11)=48/21/31 by mole.

Monomer (b):

Resins (F4) to (F12) shown in Table 5 below were synthesized in the samemanner as in Synthesis Examples 5 to 7.

TABLE 5 Resin Composition (units and molar ratio) Mw F4(F-1)/(B-20)/(B-23) = 45/25/30 5,800 F5 (F-1)/(F-21)/(B-16) = 48/33/194,500 F6 (F-22)/maleic anhydride/(B-8) = 42/39/19 8,700 F7(F-30)/(F-48)/(B-2) = 42/17/41 12,600 F8 (F-50)/(B-7)/(B-11) = 31/35/349,200 F9 (F-55)/maleic anhydride/(B-4) = 40/37/23 7,400 F10(F-16)/maleic anhydride/(B-8) = 43/34/23 6,300 F11 (F-26)/maleicanhydride/(B-12) = 40/33/27 8,900 F12 (F-31)/(F-42)/(B-8) = 44/18/3811,600

Synthesis Example 8

Synthesis of Resin (F13):

In a one-liter autoclave were charged a solution of 9.4 g (0.10 mol) ofnorbornene and 35.8 g (0.10 mol) of monomer (a) (see Synthesis Example6) in 150 ml of 1,1,2-trichlorotrifluoroethylene, and the autoclave waspressurized to 200 psi with nitrogen. To the mixture was added 20 g(0.20 mol) of tetrafluoroethylene, and the mixture was heated to 50° C.while stirring. A solution of 1.2 g of di(4-t-butylcyclohexyl)peroxydicarboxylate in 15 ml of 1,1,2-trichlorotrifluoroethylene wasadded to the reaction mixture over 20 minutes, followed by stirring for20 hours. After completion of the reaction, the reaction mixture waspoured into 2 liters of methanol with vigorous stirring. Theprecipitated white resin was collected by filtration and dried in vacuoto give 37.4 g of resin (F13).

As a result of GPC analysis, resin (F13) had a weight average molecularweight (Mw) of 8,800. C¹³-NMR analysis revealed that the composition ofresin (F13) was (F-1)/I(F-21)/norbornene=48/30/22 by mole.

Synthesis Example 9

Synthesis of Resin (F14):

Resin (F14) weighing 34.1 g was obtained in the same manner as inSynthesis Example 8, except for replacing monomer (a) with 32.2 g (0.04mol) of monomer (c) shown below.

As a result of GPC analysis, resin (F14) had a weight average molecularweight (Mw) of 7,400. C¹³-NMR analysis revealed that resin (F14) had acomposition of (F-1)/I(F-15)/norbornene=49/25/26 by mole.

Monomer (c):

Resins (F15) to (F22) shown in Table 6 were synthesized in the samemanner as in Synthesis Examples 8 and 9.

TABLE 6 Resin Composition (units and molar ratio) Mw F15(F-1)/(F-16)/norbornene = 45/26/29 8,700 F16 (F-1)/(F-20)/(B-4) =48/30/22 9,300 F17 (F-2)/(F-22)/(B-4) = 42/39/19 7,900 F18(F-7)/(F-20)/norbornene = 35/33/32 6,400 F19 (F-12)/(F-21)/norbornene =23/38/39 5,800 F20 (F-1)/(F-25)/(B-4) = 48/23/29 7,200 F21(F-1)/(F-16)/(B-16) = 34/26/40 9,500 F22 (F-1)/(F-15)/(B-16)/norbornene= 38/21/21/20 10,900

Synthesis Example 10

Synthesis of Resin (F23):

In 100 ml of MEK were dissolved 14.3 g (0.04 mol) of monomer (a) (seeSynthesis Example 6), 3.9 g (0.04 mol) of maleic anhydride, and 11.7 g(0.02 mol) of perfluorooctylethyl norbornene-2-carboxylate, and thesolution was heated to 70° C. in a nitrogen stream. To the mixture wasadded 0.2 g of a polymerization initiator V-601 (from Wako PureChemical), followed by stirring for 3 hours. To the mixture was furtheradded 0.2 g of V-601, and the stirring was continued for an additional 4hour period. The reaction mixture was poured into 1 liter of methylt-butyl ether while vigorously stirring to precipitate a white resin,which was collected by filtration and dried in vacuo to give 16.2 g ofresin (F23).

The weight average molecular weight (Mw) of resin (F23) was found to be8,700 by GPC analysis. As a result of C¹³-NMR analysis, resin (23) wasfound to have a composition of (F-21)/(F-55)/maleic anhydride=42/18/40by mole.

Synthesis Example 11

Synthesis of Resin (F24):

In 30 ml of 1-methoxy-2-propanol were dissolved 6.7 g (0.015 mol) ofmonomer (b) (see Synthesis Example 7), 2.7 g (0.005 mol) ofperfluorooctylethyl methacrylate, 1.2 g (0.005 mol) of2-methyl-2-adamantyl methacrylate, and 1.0 g (0.005 mol) of mevaloniclactone methacrylate. A solution of 0.1 g of a polymerization initiatorV-65 (from Wako Pure Chemical), 15.6 g (0.035 mol) of monomer (b), 6.4 g(0.012 mol) of perfluorooctylethyl methacrylate, 2.8 g (0.012 mol) of2-methyl-2-adamantyl methacrylate, and 2.4 g (0.012 mol) of mevaloniclactone methacrylate in 70 ml of 1-methoxy-2-propanol was added dropwiseto the monomer solution at 70° C. over 2 hours in a nitrogen streamwhile stirring. After the dropwise addition, additional 0.1 g of theinitiator was added to the mixture, followed by stirring for 2 hours.The reaction temperature was raised to 90° C., at which the stirring wascontinued for an additional 1 hour period. The reaction mixture wasallowed to cool and then poured into 1 liter of a 1/1 mixture ofion-exchanged water and methanol with vigorous stirring to precipitate awhite resin, which was collected by filtration and dried under reducedpressure to give 21.5 g of resin (F24).

As a result of GPC analysis, resin (F24) had a weight average molecularweight (Mw) of 10,500. C¹³-NMR analysis revealed that resin (F24) had acomposition of (F-30)/(F-48)/(B-7)/(B-11)=48/15/18/19 by mole.

Resins (F25) to (F32) shown in Table 7 below were synthesized in thesame manner as in Synthesis Examples 10 and 11.

TABLE 7 Resin Composition (units and molar ratio) Mw F25(F-15)/(F-58)/maleic anhydride = 30/24/46 9,700 F26(F-16)/(F-55)/(B-4)/maleic 10,600 anhydride = 26/14/22/38 F27(F-21)/(F-60)/(B-4)/maleic 8,500 anhydride = 28/14/21/37 F28(F-21)/(F-64)/maleic anhydride = 37/23/40 9,400 F29(F-25)/(F-55)/(B-4)/maleic 7,800 anhydride = 21/18/25/36 F30(F-30)/(F-50)/(B-2)/(B-12) = 45/16/15/24 10,400 F31(F-30)/(F-53)/(B-8)/(B-11) = 40/18/25/17 9,700 F32(F-30)/(F-54)/(B-7)/(B-13) = 38/15/31/16 9,900

Synthesis Example 12

Synthesis of Resin (F33):

In 100 ml of N,N-dimethylacetamide were dissolved 13.5 g (0.05 mol) of4-[bis(trifluoromethyl)hydroxymethyl]styrene and 3.4 g (0.05 mol) ofmethacrylonitrile, and the solution was heated to 70° C. in a nitrogenstream. To the solution was added 0.1 g of a polymerization initiatorV-65 (from Wako Pure Chemical), followed by stirring for 3 hours. Anadditional 0.1 g amount of V-65 was added, followed by stirring for 4hours. The reaction mixture was poured into 1 liter of methanol/methylt-butyl ether with vigorous stirring to precipitate a white resin, whichwas collected by filtration and dried in vacuo. The resin was dissolvedin 100 ml of THF, and 2.9 g (0.04 mol) of ethyl vinyl ether was addedthereto, and a catalytic amount of p-toluenesulfonic acid was furtheradded thereto. After stirring the mixture at room temperature for 8hours, twice as much triethylamine as the p-toluenesulfonic acidcatalyst was added to the reaction mixture to stop the reaction. Thereaction mixture was poured into 3 liters of ultrapure water whilevigorously stirring. The precipitated resin was collected by filtrationand dried to give 14.1 g of resin (F33).

As a result of GPC analysis, resin (F33) was found to have a weightaverage molecular weight (Mw) of 10,900. C¹³-NMR analysis revealed thatresin (F33) had a composition of (F-39)/(F-42)/(C-10)=16/36/48 by mole.

Resins (F34) to (F40) shown in Table 8 below were synthesized in thesame manner as in Synthesis Example 12.

TABLE 8 Resin Composition (units and molar ratio) Mw F34(F-39)/(F-41)/(C-10) = 14/38/48 11,100 F35 (F-44)/(C-10) = 53/47 9,800F36 (F-42)/(C-12) = 55/45 10,700 F37 (F-39)/(F-43)/(C-10) = 13/39/4812,600 F38 (F-1)/(F-21)/(C-5) = 40/35/25 6,800 F39 (F-19)/maleicanhydride/(C-8) = 35/33/32 8,300 F40 (F-1)/(B-4)/(C-8) = 43/34/23 7,400

Synthesis Example 13

Synthesis of Resin (F42):

In a 100 ml three-necked flask equipped with a reflux condenser and aninlet for nitrogen introduction were charged4-(2-hydroxyhexanefluoroisopropyl)styrene (available from Central GlassCo., Ltd.) and 4-(1-methoxyethoxy)styrene (available from Tosoh Corp.)at a molar ratio of 50/50, and THF was added thereto to prepare 30 g ofa 30 wt % monomer solution. The solution was heated to 65° C. in anitrogen stream while stirring. A polymerization initiator V-65 (fromWako Pure Chemical) was added thereto in an amount of 5.0 mol % based onthe total amount of the monomers, and the monomers were allowed topolymerize for 8 hours in a nitrogen stream while stirring. To theresulting reaction mixture was added 200 ml of hexane, and theprecipitated resin was collected to give resin (F42). Thecopolymerization ratio of resin (F42) was found to be 49/51 by C¹³-NMRanalysis.

GPC analysis (in THF) of resin (F42). revealed that the polystyreneequivalent weight average molecular weight (Mw) was 10,200, themolecular weight distribution was 2.20, and the proportion oflow-molecular components having Mw of 1000 or smaller was 15 wt %.

Resins (F41) to (F50) shown in Table 9 below were synthesized in thesame manner as in Synthesis Example 13.

TABLE 9 Resin Composition (units and molar ratio) Mw F41 (IIa-1)/(A-1) =48/52 8,900 F42 (IIa-1)/(A-2) = 49/51 10,200 F43 (IIa-1)/(A-3′) = 53/475,800 F44 (IIa-1)/(A-10) = 61/39 9,200 F45 (IIa-1)/(A-19) = 64/36 8,500F46 (IIa-1)/(A-34) = 60/40 8,600 F47 (IIa-1)/(A-35) = 51/49 8,800 F48(IIa-1)/(A-36) = 50/50 8,400 F49 (IIa-1)/(A-19) = 64/36 10,100 F50(IIa-3)/(A-20) = 61/39 9,200

Synthesis Example 14

Synthesis of Resin (k-1):

In a flask, 100 g of poly-p-hydroxystyrene (VP15000, available fromNippon Soda Co., Ltd.) was dissolved in 400 g of propylene glycolmonomethyl ether acetate (hereinafter, PGMEA), and the solution wasdistilled under reduced pressure to azeotropically remove water withPGMEA. After confirming that the water content was sufficiently reduced,25.0 g of ethyl vinyl ether and 0.02 g of p-toluenesulfonic acid wereadded thereto, followed by stirring at room temperature for 1 hour. Tothe reaction mixture was added 0.03 g of triethylamine to stop thereaction. Water (400 ml) and ethyl acetate (800 ml) were added forliquid-liquid separation. The organic layer was washed with water anddistilled under reduced pressure to remove ethyl acetate, water, andazeotropic PGMEA to give resin (k-1) (the structure is previously shown)in the form of a 30% solution in PGMEA.

Resins (k-2) to (k-15) (the structures are previously shown) weresynthesized in the same manner as in Synthesis Example 14. Thecompositions and molecular weights of resins (k-1) to (k-15) are shownin Table 10 below, in which the order of the units are the same as inthe respective structural formulae (left to right).

TABLE 10 Resin Mw Composition k-1 17,000 40/60 k-2 17,000 27/73 k-317,000 23/77 k-4 17,000 35/65 k-5 17,000 20/80 k-6 17,000 35/55/10 k-717,000 27/63/10 k-8 17,000 18/72/10 k-9 17,000 30/60/10 k-10 17,00020/75/5 k-11 12,000 70/30 k-12 13,000 10/60/30 k-13 14,000 15/60/25 k-1417,000 35/65 k-15 17,000 30/10/60

Examples 1 to 49 and Comparative Examples 1 to 10

According to the formulation shown in Tables 11 and 12 below, 1.03 g ofa resin (B), an indicated amount of a photo-acid generator (A), 0.05 gof a compound (D), 1.65 mg of an organic basic compound (C), and 100ppm, based on the total composition, of a surface active agent werecompounded and dissolved in a 7/3 (by weight) mixed solvent of propyleneglycol monomethyl ether acetate and propylene glycol monomethyl ether tomake a 11 wt % solution. The solution was microfiltered through amembrane filter having an opening size of 0.1 μm to prepare a positiveresist composition.

TABLE 11 Basic Photo-acid Com- Com- Resin Generator (A) pound pound Sur-Example (B) (mg) (D) (C) factant 1  1 z34 (16) D-1 C-1 W-1 2  2 z34/z31(16/32) D-2 C-2 W-2 3  3 z33 (16) D-3 C-3 W-3 4  4 z33 (20) D-4 C-4 W-45  5 z34 (16) D-5 c-5 W-1 6  6 z33/z40 (16/32) D-6 C-6 W-2 7  7 z14 (20)D-7 C-7 W-3 8  8 z33/z31 (16/32) D-1 C-8 W-4 9  9 z33/z31 (16/32) D-2C-9 W-1 10 10 z33/z31 (16/32) D-3 C-2 W-2 11 11 z33/z31 (16/32) D-4 C-3W-3 12 12 z33/Z31 (16/32) D-5 C-4 W-4 13 13 z33/z31 (16/32) D-6 C-10 W-114 14 z33/z31 (16/32) D-7 C-6 W-1 15 15 z33/z31 (16/32) D-1 C-7 W-2 1616 z33/z31 (16/32) D-2 C-8 W-3 17 17 z13 (16) D-3 C-1 W-4 18 18 z13 (16)D-4 C-2 W-1 19 19 z13 (16) D-5 C-3 W-2 20 20 z13 (16) D-6 C-4 W-3 21 21z13/z19 (20/40) D-7 C-5 W-4 22 22 z13/z29 (16/32) D-1 C-6 W-1 23 23 z3(16) D-2 C-7 W-2 24 24 z13 (16) D-3 C-9 W-1 25 25 z5 (16) D-4 C-1 W-2 2626 z5 (16) D-5 C-2 W-3 27 27 z5/z22 (16/32) D-6 C-3 W-4 28 28 z33/z26(16/32) D-7 C-4 W-1 29 29 z33/z27 (16/32) D-1 C-5 W-2 30 30 z13/z27(16/48) D-2 C-10 W-3 31 31 z33/z31 (16/32) D-3 C-7 W-4 32 l-1 PAG2-1(24) D-1 C-8 W-1 33 k-2 PAG2-3 (24) D-2 C-1 W-2 34 l-3 PAG2-4 (24) D-3C-2 W-3 35 k-4 PAG2-26 (24) D-4 C-3 W-4 36 k-5 PAG2-29 (24) D-5 C-4 W-137 k-8 PAG2-3/PAG2-24 D-6 C-7 W-2 (24/12) 38 k-9 PAG2-4/PAG5-3 D-7 C-8W-3 (24/24) 39 k-10 PAG2-18/PAG5-3 D-1 C-1 W-4 (24/24) 40 k-11PAG2-21/PAG6A-1 D-2 C-2 W-1 (24/24) 41 k-12 PAG2-23/PAG6A-23 D-3 C-3 W-2(24/12) 42 k-13 PAG2-1/PAG6A-10 D-4 C-4 W-3 (24/24) 43 F1 z34/z31(16/32) D-1 C-6 W-1 44 F27 z33 (20) D-2 C-4 W-2 45 F42 z33/z31 (16/32)D-3 C-7 W-3 46 F50 z13 (16) D-4 C-1 W-4 47 F25 z13/z19 (20/40) D-5 C-3W-2 48 F33 PAG2-1/PAG2-30 D-6 C-2 W-3 (24/12) 49 F18 PAG2-1 (24) D-7 C-9W-1

TABLE 12 Basic Photo-acid Com- Com- Compara. Resin Generator (A) poundpound Sur Example (B) (mg) (D) (C) factant 1 10 z33/z31 (16/32) — C-2W-2 2 11 z33/z31 (16/32) — C-3 W-3 3 12 z33/z31 (16/32) — C-4 W-4 4 13z33/z31 (16/32) — C-5 W-1 5 k-1 PAG2-1 (24) — C-8 W-1 6 k-8PAG2-3/PAG2-24 — C-7 W-2 (24/6) 7 k-12 PAG2-23/PAG6A-23 — C-3 W-2(24/12) 8 F1 z34/z31 (16/32) — C-7 W-3 9 F27 z33 (20) — C-1 W-4 10 F42PAG2-1 (24) — C-3 W-2

The components (D) and (C), and the surfactants used in Examples andComparative Examples were as follows.

Component (D):

-   D-1: Threitol-   D-2: Sorbitol-   D-3: Mannitol-   D-4: Deoxyribulose

Component (C) (Basic Compound):

-   C-1: 1,5-Diazabicyclo[4.3.0]-5-nonene-   C-2: 1,8-Diazabicyclo[5.4.0]-7-undecene-   C-3: 4-Dimethylaminopyridine-   C-4: Triphenylimidazole-   C-5: Diisopropylaniline-   C-6: Tributylamine-   C-7: Trioctylamine-   C-8: Tridodecylamine-   C-9: N,N-Bis(hydroxyethyl)aniline-   C-10: 2,2,6,6-Tetramethyl-4-hydroxypiperidine    Surface Active Agent:-   W-1: Megafac F176 (F-containing surface active agent available from    Dainippon Ink & Chemicals Inc.)-   W2: Megafac R08 (F- and Si-containing surface active agent from    Dainippon Ink & Chemical)-   W3: Polysiloxane KP-341 (Si-containing surface active agent from    Shin-Etsu Chemical Co., Ltd.)-   W4: Troy Sol S-366 (from Troy Chemical Industries, Inc.).

An antireflective coating ARC-25 (available from Brewer Science Ltd.)was applied to a silicon wafer with a spin coater to a coating thicknessof 30 nm and dried. The positive resist composition prepared was appliedto the antireflective coat and dried at 115° C. for 90 seconds to form aresist film having a thickness of about 0.4 μm.

The resist film on the wafer was exposed to ArF excimer laser light(193nm) (in Examples 1 to 31 and Comparative Examples 1 to 4), KrF excimerlaser light (248 nm) (in Examples 32 to 39 and Comparative Examples 5and 6), an electron beam (in Examples 40 to 42 and Comparative Example7), or F2 excimer laser light (157 nm) (in Examples 43 to 49 andComparative Examples 8 to 10). After post-exposure baking at 115° C. for90 seconds, the resist film was developed with a 2.38%tetramethylammonium hydroxide developing solution, rinsed with distilledwater, and dried to form a resist pattern. The resist pattern profilewas evaluated in terms of LER and pattern collapse as follows. Theresults of evaluation are shown in Table 13.

1) LER

A critical dimension scanning electron microscope (CD-SEM) was used.Irregularity of a single isolated pattern (line width: 0.15 μm) wasmeasured at more than one points within the monitoring area. A variance(3σ) of the positions was taken as an indication of LER. A smaller 3σvalue means smaller LER.

2) Pattern Collapse

The pattern profile was observed under a scanning electron microscope. Apattern suffering no or little collapse was rated “good”, while apattern suffering collapse was rated “no good”.

TABLE 13 LER Pattern (nm) Collapse Example 1 4.2 good 2 3.9 good 3 4.1good 4 3.8 good 5 7.1 good 6 4.3 good 7 4.8 good 8 4.2 good 9 3.9 good10 4.2 good 11 4.4 good 12 7.2 good 13 3.9 good 14 4.2 good 15 4.2 good16 4.4 good 17 4.1 good 18 4.2 good 19 7.1 good 20 3.9 good 21 3.9 good22 4.2 good 23 4.3 good 24 4.1 good 25 4.3 good 26 7.1 good 27 4.2 good28 4.2 good 29 4.4 good 30 4.5 good 31 3.9 good 32 4.2 good 33 4.5 good34 4.2 good 35 4.4 good 36 7.1 good 37 4.1 good 38 4.3 good 39 4.2 good40 4.4 good 41 4.1 good 42 4.2 good 43 6.1 good 44 5.9 good 45 6.3 good46 6.2 good 47 8.2 good 48 5.9 good 49 6.0 good Comparative Example 113.5 no good 2 14.1 no good 3 13.9 no good 4 14.2 no good 5 13.8 no good6 14.2 no good 7 14.1 no good 8 15.2 no good 9 14.9 no good 10 15.3 nogood

As is apparent from the results in Table 13, the positive resistcompositions of the present invention are excellent in providing aresist profile with reduced LER and reduced pattern collapse.

The present invention provides a positive resist composition which formsa resist pattern with reduced LER and reduced pattern collapse.

This application is based on Japanese Patent application JP 2002-74565,filed Mar. 18, 2002, the entire content of which is hereby incorporatedby reference, the same as if set forth at length.

1. A positive resist composition comprising: (A) a compound capable ofgenerating an acid on exposure to active light rays or a radiation; (B)a resin which is insoluble or sparingly soluble in an alkali and becomesalkali-soluble by an action of an acid; and (D) an acyclic saccharidederivative having at least three groups selected from a hydroxyl groupand a hydroxyl group substituted with an acid decomposable group;wherein the resin (B) has a structure represented by formula (pA)

wherein a plurality of R groups, which may be the same or different,each represents a hydrogen atom, a halogen atom or a substituted orun-substituted straight-chain or branched alkyl group having 1 to 4carbon atoms; A represents a single bond or one of, or a combination oftwo or more of, an alkylene group, a substituted alkylene group, anether group, a thioether group, a carbonyl group, an ester group, anamide group, a sulfonamide group, a urethane group, and a urea group;and Ra represents any one of the structures represented by formula (pI)to (pVI):

wherein R₁₁ represents a methyl group, an ethyl group, an n-propylgroup, an isopropyl group, an n-butyl group, an isobutyl group or asec-butyl group; Z represents an atomic group necessary to form analicyclic hydrocarbon group together with the adjacent carbon atom; R₁₂,R₁₃, R₁₄, R₁₅, and R₁₆ each represents a straight-chain or branchedalkyl group having 1 to 4 carbon atoms or an alicyclic hydrocarbongroup, provided that at least one of R₁₂, R₁₃, and R₁₄ and at least oneof R₁₅ and R₁₆ represents an alicyclic hydrocarbon group; R₁₇, R₁₈, R₁₉,R₂₀, and R₂₁ each represents a hydrogen atom, a straight-chain orbranched alkyl group having 1 to 4 carbon atoms or an alicyclichydrocarbon group, provided that at least one of R₁₇, R₁₈, R₁₉, R₂₀, andR₂₁ represents an alicyclic hydrocarbon group and that at least one ofR₁₉ and R₂₁ represents a straight-chain or branched alkyl group having 1to 4 carbon atoms or an alicyclic hydrocarbon group; and R₂₂, R₂₃, R₂₄,and R₂₅ each represents a straight-chain or branched alkyl group having1 to 4 carbon atoms or an alicyclic hydrocarbon group, provided that atleast one of R₂₂, R₂₃, R₂₄, and R₂₅ represents an alicyclic hydrocarbongroup; and R₂₃, and R₂₄ may be connected together to form a ring.
 2. Thepositive resist composition according to claim 1, wherein the resin (B)has a structure comprising a fluorine atom substituting at least one ofa main chain and a side chain of a polymer skeleton and decomposes by anaction of an acid to increase its solubility in an alkali developingsolution.
 3. The positive resist composition according to claim 1, whichfurther comprises (C) a basic compound.
 4. The positive resistcomposition according to claim 1, which further comprises (E) a surfaceactive agent comprising at least one of fluorine and silicon.
 5. Thepositive resist composition according to claim 1, which furthercomprises (F) a mixed solvent comprising a solvent having a hydroxylgroup and a solvent free from a hydroxyl group.
 6. The positive resistcomposition according to claim 1, wherein the acid decomposable group isselected from the group consisting of an acetal group, isopropylidenegroup and a cyclohexylidene group.
 7. The positive resist compositionaccording to claim 1, wherein the acid decomposable group is selectedfrom the group consisting of an isopropylidene group and acyclohexylidene group.
 8. A positive resist composition comprising: (A)a compound capable of generating an acid on exposure to active lightrays or a radiation; (B) a resin which is insoluble or sparingly solublein an alkali and becomes alkali-soluble by an action of an acid, saidresin having a structure comprising a fluorine atom substituting atleast one of a main chain and a side chain of a polymer skeleton anddecomposing by an action of an acid to increase its solubility in analkali developing solution; and (D) an acyclic saccharide derivativehaving at least three groups selected from a hydroxyl group and ahydroxyl group substituted with an acid decomposable group.
 9. Thepositive resist composition according to claim 8, which furthercomprises (C) a basic compound.
 10. The positive resist compositionaccording to claim 8, which further comprises (E) a surface active agentcomprising at least one of fluorine and silicon.
 11. The positive resistcomposition according to claim 8, which further comprises (F) a mixedsolvent comprising a solvent having a hydroxyl group and a solvent freefrom a hydroxyl group.
 12. The positive resist composition according toclaim 8, wherein the acid decomposable group is selected from the groupconsisting of an acetal group, isopropylidene group and acyclohexylidene group.
 13. The positive resist composition according toclaim 8, wherein the acid decomposable group is selected from the groupconsisting of an isopropylidene group and a cyclohexylidene group.